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I threw some code together to flatten and un-flatten complex/nested JavaScript objects. It works, but it's a bit slow (triggers the 'long script' warning).
For the flattened names I want "." as the delimiter and [INDEX] for arrays.
Examples:
un-flattened | flattened
---------------------------
{foo:{bar:false}} => {"foo.bar":false}
{a:[{b:["c","d"]}]} => {"a[0].b[0]":"c","a[0].b[1]":"d"}
[1,[2,[3,4],5],6] => {"[0]":1,"[1].[0]":2,"[1].[1].[0]":3,"[1].[1].[1]":4,"[1].[2]":5,"[2]":6}
I created a benchmark that ~simulates my use case http://jsfiddle.net/WSzec/
Get a nested object
Flatten it
Look through it and possibly modify it while flattened
Unflatten it back to it's original nested format to be shipped away
I would like faster code: For clarification, code that completes the JSFiddle benchmark (http://jsfiddle.net/WSzec/) significantly faster (~20%+ would be nice) in IE 9+, FF 24+, and Chrome 29+.
Here's the relevant JavaScript code: Current Fastest: http://jsfiddle.net/WSzec/6/
var unflatten = function(data) {
"use strict";
if (Object(data) !== data || Array.isArray(data))
return data;
var result = {}, cur, prop, idx, last, temp;
for(var p in data) {
cur = result, prop = "", last = 0;
do {
idx = p.indexOf(".", last);
temp = p.substring(last, idx !== -1 ? idx : undefined);
cur = cur[prop] || (cur[prop] = (!isNaN(parseInt(temp)) ? [] : {}));
prop = temp;
last = idx + 1;
} while(idx >= 0);
cur[prop] = data[p];
}
return result[""];
}
var flatten = function(data) {
var result = {};
function recurse (cur, prop) {
if (Object(cur) !== cur) {
result[prop] = cur;
} else if (Array.isArray(cur)) {
for(var i=0, l=cur.length; i<l; i++)
recurse(cur[i], prop ? prop+"."+i : ""+i);
if (l == 0)
result[prop] = [];
} else {
var isEmpty = true;
for (var p in cur) {
isEmpty = false;
recurse(cur[p], prop ? prop+"."+p : p);
}
if (isEmpty)
result[prop] = {};
}
}
recurse(data, "");
return result;
}
EDIT 1 Modified the above to #Bergi 's implementation which is currently the fastest. As an aside, using ".indexOf" instead of "regex.exec" is around 20% faster in FF but 20% slower in Chrome; so I'll stick with the regex since it's simpler (here's my attempt at using indexOf to replace the regex http://jsfiddle.net/WSzec/2/).
EDIT 2 Building on #Bergi 's idea I managed to created a faster non-regex version (3x faster in FF and ~10% faster in Chrome). http://jsfiddle.net/WSzec/6/ In the this (the current) implementation the rules for key names are simply, keys cannot start with an integer or contain a period.
Example:
{"foo":{"bar":[0]}} => {"foo.bar.0":0}
EDIT 3 Adding #AaditMShah 's inline path parsing approach (rather than String.split) helped to improve the unflatten performance. I'm very happy with the overall performance improvement reached.
The latest jsfiddle and jsperf:
http://jsfiddle.net/WSzec/14/
http://jsperf.com/flatten-un-flatten/4
Here's my much shorter implementation:
Object.unflatten = function(data) {
"use strict";
if (Object(data) !== data || Array.isArray(data))
return data;
var regex = /\.?([^.\[\]]+)|\[(\d+)\]/g,
resultholder = {};
for (var p in data) {
var cur = resultholder,
prop = "",
m;
while (m = regex.exec(p)) {
cur = cur[prop] || (cur[prop] = (m[2] ? [] : {}));
prop = m[2] || m[1];
}
cur[prop] = data[p];
}
return resultholder[""] || resultholder;
};
flatten hasn't changed much (and I'm not sure whether you really need those isEmpty cases):
Object.flatten = function(data) {
var result = {};
function recurse (cur, prop) {
if (Object(cur) !== cur) {
result[prop] = cur;
} else if (Array.isArray(cur)) {
for(var i=0, l=cur.length; i<l; i++)
recurse(cur[i], prop + "[" + i + "]");
if (l == 0)
result[prop] = [];
} else {
var isEmpty = true;
for (var p in cur) {
isEmpty = false;
recurse(cur[p], prop ? prop+"."+p : p);
}
if (isEmpty && prop)
result[prop] = {};
}
}
recurse(data, "");
return result;
}
Together, they run your benchmark in about the half of the time (Opera 12.16: ~900ms instead of ~ 1900ms, Chrome 29: ~800ms instead of ~1600ms).
Note: This and most other solutions answered here focus on speed and are susceptible to prototype pollution and shold not be used on untrusted objects.
I wrote two functions to flatten and unflatten a JSON object.
Flatten a JSON object:
var flatten = (function (isArray, wrapped) {
return function (table) {
return reduce("", {}, table);
};
function reduce(path, accumulator, table) {
if (isArray(table)) {
var length = table.length;
if (length) {
var index = 0;
while (index < length) {
var property = path + "[" + index + "]", item = table[index++];
if (wrapped(item) !== item) accumulator[property] = item;
else reduce(property, accumulator, item);
}
} else accumulator[path] = table;
} else {
var empty = true;
if (path) {
for (var property in table) {
var item = table[property], property = path + "." + property, empty = false;
if (wrapped(item) !== item) accumulator[property] = item;
else reduce(property, accumulator, item);
}
} else {
for (var property in table) {
var item = table[property], empty = false;
if (wrapped(item) !== item) accumulator[property] = item;
else reduce(property, accumulator, item);
}
}
if (empty) accumulator[path] = table;
}
return accumulator;
}
}(Array.isArray, Object));
Performance:
It's faster than the current solution in Opera. The current solution is 26% slower in Opera.
It's faster than the current solution in Firefox. The current solution is 9% slower in Firefox.
It's faster than the current solution in Chrome. The current solution is 29% slower in Chrome.
Unflatten a JSON object:
function unflatten(table) {
var result = {};
for (var path in table) {
var cursor = result, length = path.length, property = "", index = 0;
while (index < length) {
var char = path.charAt(index);
if (char === "[") {
var start = index + 1,
end = path.indexOf("]", start),
cursor = cursor[property] = cursor[property] || [],
property = path.slice(start, end),
index = end + 1;
} else {
var cursor = cursor[property] = cursor[property] || {},
start = char === "." ? index + 1 : index,
bracket = path.indexOf("[", start),
dot = path.indexOf(".", start);
if (bracket < 0 && dot < 0) var end = index = length;
else if (bracket < 0) var end = index = dot;
else if (dot < 0) var end = index = bracket;
else var end = index = bracket < dot ? bracket : dot;
var property = path.slice(start, end);
}
}
cursor[property] = table[path];
}
return result[""];
}
Performance:
It's faster than the current solution in Opera. The current solution is 5% slower in Opera.
It's slower than the current solution in Firefox. My solution is 26% slower in Firefox.
It's slower than the current solution in Chrome. My solution is 6% slower in Chrome.
Flatten and unflatten a JSON object:
Overall my solution performs either equally well or even better than the current solution.
Performance:
It's faster than the current solution in Opera. The current solution is 21% slower in Opera.
It's as fast as the current solution in Firefox.
It's faster than the current solution in Firefox. The current solution is 20% slower in Chrome.
Output format:
A flattened object uses the dot notation for object properties and the bracket notation for array indices:
{foo:{bar:false}} => {"foo.bar":false}
{a:[{b:["c","d"]}]} => {"a[0].b[0]":"c","a[0].b[1]":"d"}
[1,[2,[3,4],5],6] => {"[0]":1,"[1][0]":2,"[1][1][0]":3,"[1][1][1]":4,"[1][2]":5,"[2]":6}
In my opinion this format is better than only using the dot notation:
{foo:{bar:false}} => {"foo.bar":false}
{a:[{b:["c","d"]}]} => {"a.0.b.0":"c","a.0.b.1":"d"}
[1,[2,[3,4],5],6] => {"0":1,"1.0":2,"1.1.0":3,"1.1.1":4,"1.2":5,"2":6}
Advantages:
Flattening an object is faster than the current solution.
Flattening and unflattening an object is as fast as or faster than the current solution.
Flattened objects use both the dot notation and the bracket notation for readability.
Disadvantages:
Unflattening an object is slower than the current solution in most (but not all) cases.
The current JSFiddle demo gave the following values as output:
Nested : 132175 : 63
Flattened : 132175 : 564
Nested : 132175 : 54
Flattened : 132175 : 508
My updated JSFiddle demo gave the following values as output:
Nested : 132175 : 59
Flattened : 132175 : 514
Nested : 132175 : 60
Flattened : 132175 : 451
I'm not really sure what that means, so I'll stick with the jsPerf results. After all jsPerf is a performance benchmarking utility. JSFiddle is not.
ES6 version:
const flatten = (obj, path = '') => {
if (!(obj instanceof Object)) return {[path.replace(/\.$/g, '')]:obj};
return Object.keys(obj).reduce((output, key) => {
return obj instanceof Array ?
{...output, ...flatten(obj[key], path + '[' + key + '].')}:
{...output, ...flatten(obj[key], path + key + '.')};
}, {});
}
Example:
console.log(flatten({a:[{b:["c","d"]}]}));
console.log(flatten([1,[2,[3,4],5],6]));
3 ½ Years later...
For my own project I wanted to flatten JSON objects in mongoDB dot notation and came up with a simple solution:
/**
* Recursively flattens a JSON object using dot notation.
*
* NOTE: input must be an object as described by JSON spec. Arbitrary
* JS objects (e.g. {a: () => 42}) may result in unexpected output.
* MOREOVER, it removes keys with empty objects/arrays as value (see
* examples bellow).
*
* #example
* // returns {a:1, 'b.0.c': 2, 'b.0.d.e': 3, 'b.1': 4}
* flatten({a: 1, b: [{c: 2, d: {e: 3}}, 4]})
* // returns {a:1, 'b.0.c': 2, 'b.0.d.e.0': true, 'b.0.d.e.1': false, 'b.0.d.e.2.f': 1}
* flatten({a: 1, b: [{c: 2, d: {e: [true, false, {f: 1}]}}]})
* // return {a: 1}
* flatten({a: 1, b: [], c: {}})
*
* #param obj item to be flattened
* #param {Array.string} [prefix=[]] chain of prefix joined with a dot and prepended to key
* #param {Object} [current={}] result of flatten during the recursion
*
* #see https://docs.mongodb.com/manual/core/document/#dot-notation
*/
function flatten (obj, prefix, current) {
prefix = prefix || []
current = current || {}
// Remember kids, null is also an object!
if (typeof (obj) === 'object' && obj !== null) {
Object.keys(obj).forEach(key => {
this.flatten(obj[key], prefix.concat(key), current)
})
} else {
current[prefix.join('.')] = obj
}
return current
}
Features and/or caveats
It only accepts JSON objects. So if you pass something like {a: () => {}} you might not get what you wanted!
It removes empty arrays and objects. So this {a: {}, b: []} is flattened to {}.
Use this library:
npm install flat
Usage (from https://www.npmjs.com/package/flat):
Flatten:
var flatten = require('flat')
flatten({
key1: {
keyA: 'valueI'
},
key2: {
keyB: 'valueII'
},
key3: { a: { b: { c: 2 } } }
})
// {
// 'key1.keyA': 'valueI',
// 'key2.keyB': 'valueII',
// 'key3.a.b.c': 2
// }
Un-flatten:
var unflatten = require('flat').unflatten
unflatten({
'three.levels.deep': 42,
'three.levels': {
nested: true
}
})
// {
// three: {
// levels: {
// deep: 42,
// nested: true
// }
// }
// }
Here's another approach that runs slower (about 1000ms) than the above answer, but has an interesting idea :-)
Instead of iterating through each property chain, it just picks the last property and uses a look-up-table for the rest to store the intermediate results. This look-up-table will be iterated until there are no property chains left and all values reside on uncocatenated properties.
JSON.unflatten = function(data) {
"use strict";
if (Object(data) !== data || Array.isArray(data))
return data;
var regex = /\.?([^.\[\]]+)$|\[(\d+)\]$/,
props = Object.keys(data),
result, p;
while(p = props.shift()) {
var m = regex.exec(p),
target;
if (m.index) {
var rest = p.slice(0, m.index);
if (!(rest in data)) {
data[rest] = m[2] ? [] : {};
props.push(rest);
}
target = data[rest];
} else {
target = result || (result = (m[2] ? [] : {}));
}
target[m[2] || m[1]] = data[p];
}
return result;
};
It currently uses the data input parameter for the table, and puts lots of properties on it - a non-destructive version should be possible as well. Maybe a clever lastIndexOf usage performs better than the regex (depends on the regex engine).
See it in action here.
You can use https://github.com/hughsk/flat
Take a nested Javascript object and flatten it, or unflatten an object with delimited keys.
Example from the doc
var flatten = require('flat')
flatten({
key1: {
keyA: 'valueI'
},
key2: {
keyB: 'valueII'
},
key3: { a: { b: { c: 2 } } }
})
// {
// 'key1.keyA': 'valueI',
// 'key2.keyB': 'valueII',
// 'key3.a.b.c': 2
// }
var unflatten = require('flat').unflatten
unflatten({
'three.levels.deep': 42,
'three.levels': {
nested: true
}
})
// {
// three: {
// levels: {
// deep: 42,
// nested: true
// }
// }
// }
This code recursively flattens out JSON objects.
I included my timing mechanism in the code and it gives me 1ms but I'm not sure if that's the most accurate one.
var new_json = [{
"name": "fatima",
"age": 25,
"neighbour": {
"name": "taqi",
"location": "end of the street",
"property": {
"built in": 1990,
"owned": false,
"years on market": [1990, 1998, 2002, 2013],
"year short listed": [], //means never
}
},
"town": "Mountain View",
"state": "CA"
},
{
"name": "qianru",
"age": 20,
"neighbour": {
"name": "joe",
"location": "opposite to the park",
"property": {
"built in": 2011,
"owned": true,
"years on market": [1996, 2011],
"year short listed": [], //means never
}
},
"town": "Pittsburgh",
"state": "PA"
}]
function flatten(json, flattened, str_key) {
for (var key in json) {
if (json.hasOwnProperty(key)) {
if (json[key] instanceof Object && json[key] != "") {
flatten(json[key], flattened, str_key + "." + key);
} else {
flattened[str_key + "." + key] = json[key];
}
}
}
}
var flattened = {};
console.time('flatten');
flatten(new_json, flattened, "");
console.timeEnd('flatten');
for (var key in flattened){
console.log(key + ": " + flattened[key]);
}
Output:
flatten: 1ms
.0.name: fatima
.0.age: 25
.0.neighbour.name: taqi
.0.neighbour.location: end of the street
.0.neighbour.property.built in: 1990
.0.neighbour.property.owned: false
.0.neighbour.property.years on market.0: 1990
.0.neighbour.property.years on market.1: 1998
.0.neighbour.property.years on market.2: 2002
.0.neighbour.property.years on market.3: 2013
.0.neighbour.property.year short listed:
.0.town: Mountain View
.0.state: CA
.1.name: qianru
.1.age: 20
.1.neighbour.name: joe
.1.neighbour.location: opposite to the park
.1.neighbour.property.built in: 2011
.1.neighbour.property.owned: true
.1.neighbour.property.years on market.0: 1996
.1.neighbour.property.years on market.1: 2011
.1.neighbour.property.year short listed:
.1.town: Pittsburgh
.1.state: PA
Here's mine. It runs in <2ms in Google Apps Script on a sizable object. It uses dashes instead of dots for separators, and it doesn't handle arrays specially like in the asker's question, but this is what I wanted for my use.
function flatten (obj) {
var newObj = {};
for (var key in obj) {
if (typeof obj[key] === 'object' && obj[key] !== null) {
var temp = flatten(obj[key])
for (var key2 in temp) {
newObj[key+"-"+key2] = temp[key2];
}
} else {
newObj[key] = obj[key];
}
}
return newObj;
}
Example:
var test = {
a: 1,
b: 2,
c: {
c1: 3.1,
c2: 3.2
},
d: 4,
e: {
e1: 5.1,
e2: 5.2,
e3: {
e3a: 5.31,
e3b: 5.32
},
e4: 5.4
},
f: 6
}
Logger.log("start");
Logger.log(JSON.stringify(flatten(test),null,2));
Logger.log("done");
Example output:
[17-02-08 13:21:05:245 CST] start
[17-02-08 13:21:05:246 CST] {
"a": 1,
"b": 2,
"c-c1": 3.1,
"c-c2": 3.2,
"d": 4,
"e-e1": 5.1,
"e-e2": 5.2,
"e-e3-e3a": 5.31,
"e-e3-e3b": 5.32,
"e-e4": 5.4,
"f": 6
}
[17-02-08 13:21:05:247 CST] done
Object.prototype.flatten = function (obj) {
let ans = {};
let anotherObj = { ...obj };
function performFlatten(anotherObj) {
Object.keys(anotherObj).forEach((key, idx) => {
if (typeof anotherObj[key] !== 'object') {
ans[key] = anotherObj[key];
console.log('ans so far : ', ans);
} else {
console.log(key, { ...anotherObj[key] });
performFlatten(anotherObj[key]);
}
})
}
performFlatten(anotherObj);
return ans;
}
let ans = flatten(obj);
console.log(ans);
I added +/- 10-15% efficiency to the selected answer by minor code refactoring and moving the recursive function outside of the function namespace.
See my question: Are namespaced functions reevaluated on every call? for why this slows nested functions down.
function _flatten (target, obj, path) {
var i, empty;
if (obj.constructor === Object) {
empty = true;
for (i in obj) {
empty = false;
_flatten(target, obj[i], path ? path + '.' + i : i);
}
if (empty && path) {
target[path] = {};
}
}
else if (obj.constructor === Array) {
i = obj.length;
if (i > 0) {
while (i--) {
_flatten(target, obj[i], path + '[' + i + ']');
}
} else {
target[path] = [];
}
}
else {
target[path] = obj;
}
}
function flatten (data) {
var result = {};
_flatten(result, data, null);
return result;
}
See benchmark.
Here's a recursive solution for flatten I put together in PowerShell:
#---helper function for ConvertTo-JhcUtilJsonTable
#
function getNodes {
param (
[Parameter(Mandatory)]
[System.Object]
$job,
[Parameter(Mandatory)]
[System.String]
$path
)
$t = $job.GetType()
$ct = 0
$h = #{}
if ($t.Name -eq 'PSCustomObject') {
foreach ($m in Get-Member -InputObject $job -MemberType NoteProperty) {
getNodes -job $job.($m.Name) -path ($path + '.' + $m.Name)
}
}
elseif ($t.Name -eq 'Object[]') {
foreach ($o in $job) {
getNodes -job $o -path ($path + "[$ct]")
$ct++
}
}
else {
$h[$path] = $job
$h
}
}
#---flattens a JSON document object into a key value table where keys are proper JSON paths corresponding to their value
#
function ConvertTo-JhcUtilJsonTable {
param (
[Parameter(Mandatory = $true, ValueFromPipeline = $true)]
[System.Object[]]
$jsonObj
)
begin {
$rootNode = 'root'
}
process {
foreach ($o in $jsonObj) {
$table = getNodes -job $o -path $rootNode
# $h = #{}
$a = #()
$pat = '^' + $rootNode
foreach ($i in $table) {
foreach ($k in $i.keys) {
# $h[$k -replace $pat, ''] = $i[$k]
$a += New-Object -TypeName psobject -Property #{'Key' = $($k -replace $pat, ''); 'Value' = $i[$k]}
# $h[$k -replace $pat, ''] = $i[$k]
}
}
# $h
$a
}
}
end{}
}
Example:
'{"name": "John","Address": {"house": "1234", "Street": "Boogie Ave"}, "pets": [{"Type": "Dog", "Age": 4, "Toys": ["rubberBall", "rope"]},{"Type": "Cat", "Age": 7, "Toys": ["catNip"]}]}' | ConvertFrom-Json | ConvertTo-JhcUtilJsonTable
Key Value
--- -----
.Address.house 1234
.Address.Street Boogie Ave
.name John
.pets[0].Age 4
.pets[0].Toys[0] rubberBall
.pets[0].Toys[1] rope
.pets[0].Type Dog
.pets[1].Age 7
.pets[1].Toys[0] catNip
.pets[1].Type Cat
I wanted an approach so that I could be able to easily convert my json data into a csv file.
The scenario is: I query data from somewhere and I receive an array of some model, like a bank extract.
This approach below is used to parse each one of these entries.
function jsonFlatter(data, previousKey, obj) {
obj = obj || {}
previousKey = previousKey || ""
Object.keys(data).map(key => {
let newKey = `${previousKey}${previousKey ? "_" : ""}${key}`
let _value = data[key]
let isArray = Array.isArray(_value)
if (typeof _value !== "object" || isArray || _value == null) {
if (isArray) {
_value = JSON.stringify(_value)
} else if (_value == null) {
_value = "null"
}
obj[newKey] = _value
} else if (typeof _value === "object") {
if (!Object.keys(_value).length) {
obj[newKey] = "null"
} else {
return jsonFlatter(_value, newKey, obj)
}
}
})
return obj
}
This way, I can count on the uniformity of the keys and inner keys of my object model, but arrays are simply stringified since I can't rely on their uniformity. Also, empty objects become the string "null", since I still want it's key to appear in the final result.
Usage example:
const test_data = {
a: {
aa: {
aaa: 4354,
aab: 654
},
ab: 123
},
b: 234,
c: {},
d: []
}
console.log('result', jsonFlatter(test_data))
#### output
{
"a_aa_aaa": 4354,
"a_aa_aab": 654,
"a_ab": 123,
"b": 234,
"c": "null",
"d": "[]"
}
try this one:
function getFlattenObject(data, response = {}) {
for (const key in data) {
if (typeof data[key] === 'object' && !Array.isArray(data[key])) {
getFlattenObject(data[key], response);
} else {
response[key] = data[key];
}
}
return response;
}
I'd like to add a new version of flatten case (this is what i needed :)) which, according to my probes with the above jsFiddler, is slightly faster then the currently selected one.
Moreover, me personally see this snippet a bit more readable, which is of course important for multi-developer projects.
function flattenObject(graph) {
let result = {},
item,
key;
function recurr(graph, path) {
if (Array.isArray(graph)) {
graph.forEach(function (itm, idx) {
key = path + '[' + idx + ']';
if (itm && typeof itm === 'object') {
recurr(itm, key);
} else {
result[key] = itm;
}
});
} else {
Reflect.ownKeys(graph).forEach(function (p) {
key = path + '.' + p;
item = graph[p];
if (item && typeof item === 'object') {
recurr(item, key);
} else {
result[key] = item;
}
});
}
}
recurr(graph, '');
return result;
}
Here is some code I wrote to flatten an object I was working with. It creates a new class that takes every nested field and brings it into the first layer. You could modify it to unflatten by remembering the original placement of the keys. It also assumes the keys are unique even across nested objects. Hope it helps.
class JSONFlattener {
ojson = {}
flattenedjson = {}
constructor(original_json) {
this.ojson = original_json
this.flattenedjson = {}
this.flatten()
}
flatten() {
Object.keys(this.ojson).forEach(function(key){
if (this.ojson[key] == null) {
} else if (this.ojson[key].constructor == ({}).constructor) {
this.combine(new JSONFlattener(this.ojson[key]).returnJSON())
} else {
this.flattenedjson[key] = this.ojson[key]
}
}, this)
}
combine(new_json) {
//assumes new_json is a flat array
Object.keys(new_json).forEach(function(key){
if (!this.flattenedjson.hasOwnProperty(key)) {
this.flattenedjson[key] = new_json[key]
} else {
console.log(key+" is a duplicate key")
}
}, this)
}
returnJSON() {
return this.flattenedjson
}
}
console.log(new JSONFlattener(dad_dictionary).returnJSON())
As an example, it converts
nested_json = {
"a": {
"b": {
"c": {
"d": {
"a": 0
}
}
}
},
"z": {
"b":1
},
"d": {
"c": {
"c": 2
}
}
}
into
{ a: 0, b: 1, c: 2 }
You can try out the package jpflat.
It flattens, inflates, resolves promises, flattens arrays, has customizable path creation and customizable value serialization.
The reducers and serializers receive the whole path as an array of it's parts, so more complex operations can be done to the path instead of modifying a single key or changing the delimiter.
Json path is the default, hence "jp"flat.
https://www.npmjs.com/package/jpflat
let flatFoo = await require('jpflat').flatten(foo)
Is there a fast and simple way to encode a JavaScript object into a string that I can pass via a GET request?
No jQuery, no other frameworks—just plain JavaScript :)
Like this:
serialize = function(obj) {
var str = [];
for (var p in obj)
if (obj.hasOwnProperty(p)) {
str.push(encodeURIComponent(p) + "=" + encodeURIComponent(obj[p]));
}
return str.join("&");
}
console.log(serialize({
foo: "hi there",
bar: "100%"
}));
// foo=hi%20there&bar=100%25
This one also converts recursive objects (using PHP "array" notation for the query string):
serialize = function(obj, prefix) {
var str = [],
p;
for (p in obj) {
if (obj.hasOwnProperty(p)) {
var k = prefix ? prefix + "[" + p + "]" : p,
v = obj[p];
str.push((v !== null && typeof v === "object") ?
serialize(v, k) :
encodeURIComponent(k) + "=" + encodeURIComponent(v));
}
}
return str.join("&");
}
console.log(serialize({
foo: "hi there",
bar: {
blah: 123,
quux: [1, 2, 3]
}
}));
// foo=hi%20there&bar%5Bblah%5D=123&bar%5Bquux%5D%5B0%5D=1&bar%5Bquux%5D%5B1%5D=2&bar%5Bquux%5D%5B2%5D=3
Just use URLSearchParams This works in all current browsers
new URLSearchParams(object).toString()
jQuery has a function for this, jQuery.param(). If you're already using it, you can use this:
Example:
var params = { width:1680, height:1050 };
var str = jQuery.param( params );
str now contains width=1680&height=1050.
I suggest using the URLSearchParams interface:
const searchParams = new URLSearchParams();
const params = {foo: "hi there", bar: "100%" };
Object.keys(params).forEach(key => searchParams.append(key, params[key]));
console.log(searchParams.toString())
Or by passing the search object into the constructor like this:
const params = {foo: "hi there", bar: "100%" };
const queryString = new URLSearchParams(params).toString();
console.log(queryString);
Use:
Object.keys(obj).reduce(function(a,k){a.push(k+'='+encodeURIComponent(obj[k]));return a},[]).join('&')
I like this one-liner, but I bet it would be a more popular answer if it matched the accepted answer semantically:
function serialize( obj ) {
let str = '?' + Object.keys(obj).reduce(function(a, k){
a.push(k + '=' + encodeURIComponent(obj[k]));
return a;
}, []).join('&');
return str;
}
Here's a one liner in ES6:
Object.keys(obj).map(k => `${encodeURIComponent(k)}=${encodeURIComponent(obj[k])}`).join('&');
With Node.js v6.6.3
const querystring = require('querystring')
const obj = {
foo: 'bar',
baz: 'tor'
}
let result = querystring.stringify(obj)
// foo=bar&baz=tor
Reference: Query string
Ruby on Rails and PHP style query builder
This method converts a JavaScript object into a URI query string. It also handles nested arrays and objects (in Ruby on Rails and PHP syntax):
function serializeQuery(params, prefix) {
const query = Object.keys(params).map((key) => {
const value = params[key];
if (params.constructor === Array)
key = `${prefix}[]`;
else if (params.constructor === Object)
key = (prefix ? `${prefix}[${key}]` : key);
if (typeof value === 'object')
return serializeQuery(value, key);
else
return `${key}=${encodeURIComponent(value)}`;
});
return [].concat.apply([], query).join('&');
}
Example Usage:
let params = {
a: 100,
b: 'has spaces',
c: [1, 2, 3],
d: { x: 9, y: 8}
}
serializeQuery(params)
// returns 'a=100&b=has%20spaces&c[]=1&c[]=2&c[]=3&d[x]=9&d[y]=8
A small amendment to the accepted solution by user187291:
serialize = function(obj) {
var str = [];
for(var p in obj){
if (obj.hasOwnProperty(p)) {
str.push(encodeURIComponent(p) + "=" + encodeURIComponent(obj[p]));
}
}
return str.join("&");
}
Checking for hasOwnProperty on the object makes JSLint and JSHint happy, and it prevents accidentally serializing methods of the object or other stuff if the object is anything but a simple dictionary. See the paragraph on for statements on Code Conventions for the JavaScript Programming Language.
Well, everyone seems to put his one-liner here so here goes mine:
const encoded = Object.entries(obj).map(([k, v]) => `${k}=${encodeURIComponent(v)}`).join("&");
If you need to send arbitrary objects, then GET is a bad idea since there are limits to the lengths of URLs that user agents and web servers will accepts. My suggestion would be to build up an array of name-value pairs to send and then build up a query string:
function QueryStringBuilder() {
var nameValues = [];
this.add = function(name, value) {
nameValues.push( {name: name, value: value} );
};
this.toQueryString = function() {
var segments = [], nameValue;
for (var i = 0, len = nameValues.length; i < len; i++) {
nameValue = nameValues[i];
segments[i] = encodeURIComponent(nameValue.name) + "=" + encodeURIComponent(nameValue.value);
}
return segments.join("&");
};
}
var qsb = new QueryStringBuilder();
qsb.add("veg", "cabbage");
qsb.add("vegCount", "5");
alert( qsb.toQueryString() );
A little bit look better
objectToQueryString(obj, prefix) {
return Object.keys(obj).map(objKey => {
if (obj.hasOwnProperty(objKey)) {
const key = prefix ? `${prefix}[${objKey}]` : objKey;
const value = obj[objKey];
return typeof value === "object" ?
this.objectToQueryString(value, key) :
`${encodeURIComponent(key)}=${encodeURIComponent(value)}`;
}
return null;
}).join("&");
}
This one skips null/undefined values
export function urlEncodeQueryParams(data) {
const params = Object.keys(data).map(key => data[key] ? `${encodeURIComponent(key)}=${encodeURIComponent(data[key])}` : '');
return params.filter(value => !!value).join('&');
}
Here's the CoffeeScript version of the accepted answer.
serialize = (obj, prefix) ->
str = []
for p, v of obj
k = if prefix then prefix + "[" + p + "]" else p
if typeof v == "object"
str.push(serialize(v, k))
else
str.push(encodeURIComponent(k) + "=" + encodeURIComponent(v))
str.join("&")
Here's a concise & recursive version with Object.entries. It handles arbitrarily nested arrays, but not nested objects. It also removes empty elements:
const format = (k,v) => v !== null ? `${k}=${encodeURIComponent(v)}` : ''
const to_qs = (obj) => {
return [].concat(...Object.entries(obj)
.map(([k,v]) => Array.isArray(v)
? v.map(arr => to_qs({[k]:arr}))
: format(k,v)))
.filter(x => x)
.join('&');
}
E.g.:
let json = {
a: [1, 2, 3],
b: [], // omit b
c: 1,
d: "test&encoding", // uriencode
e: [[4,5],[6,7]], // flatten this
f: null, // omit nulls
g: 0
};
let qs = to_qs(json)
=> "a=1&a=2&a=3&c=1&d=test%26encoding&e=4&e=5&e=6&e=7&g=0"
Use:
const toQueryString = obj => "?".concat(Object.keys(obj).map(e => `${encodeURIComponent(e)}=${encodeURIComponent(obj[e])}`).join("&"));
const data = {
offset: 5,
limit: 10
};
toQueryString(data); // => ?offset=5&limit=10
Or use a predefined feature
const data = {
offset: 5,
limit: 10
};
new URLSearchParams(data).toString(); // => ?offset=5&limit=10
Note
Both the above methods will set the value as null if not present.
If you want not to set the query parameter if value is null then use:
const toQueryString = obj => "?".concat(Object.keys(obj).map(e => obj[e] ? `${encodeURIComponent(e)}=${encodeURIComponent(obj[e])}` : null).filter(e => !!e).join("&"));
const data = {
offset: null,
limit: 10
};
toQueryString(data); // => "?limit=10" else with above methods "?offset=null&limit=10"
You can freely use any method.
In ES7 you can write this in one line:
const serialize = (obj) => (Object.entries(obj).map(i => [i[0], encodeURIComponent(i[1])].join('=')).join('&'))
I have a simpler solution that does not use any third-party library and is already apt to be used in any browser that has "Object.keys" (aka all modern browsers + edge + ie):
In ES5
function(a){
if( typeof(a) !== 'object' )
return '';
return `?${Object.keys(a).map(k=>`${k}=${a[k]}`).join('&')}`;
}
In ES3
function(a){
if( typeof(a) !== 'object' )
return '';
return '?' + Object.keys(a).map(function(k){ return k + '=' + a[k] }).join('&');
}
I made a comparison of JSON stringifiers and the results are as follows:
JSON: {"_id":"5973782bdb9a930533b05cb2","isActive":true,"balance":"$1,446.35","age":32,"name":"Logan Keller","email":"logankeller#artiq.com","phone":"+1 (952) 533-2258","friends":[{"id":0,"name":"Colon Salazar"},{"id":1,"name":"French Mcneil"},{"id":2,"name":"Carol Martin"}],"favoriteFruit":"banana"}
Rison: (_id:'5973782bdb9a930533b05cb2',age:32,balance:'$1,446.35',email:'logankeller#artiq.com',favoriteFruit:banana,friends:!((id:0,name:'Colon Salazar'),(id:1,name:'French Mcneil'),(id:2,name:'Carol Martin')),isActive:!t,name:'Logan Keller',phone:'+1 (952) 533-2258')
O-Rison: _id:'5973782bdb9a930533b05cb2',age:32,balance:'$1,446.35',email:'logankeller#artiq.com',favoriteFruit:banana,friends:!((id:0,name:'Colon Salazar'),(id:1,name:'French Mcneil'),(id:2,name:'Carol Martin')),isActive:!t,name:'Logan Keller',phone:'+1 (952) 533-2258'
JSURL: ~(_id~'5973782bdb9a930533b05cb2~isActive~true~balance~'!1*2c446.35~age~32~name~'Logan*20Keller~email~'logankeller*40artiq.com~phone~'*2b1*20*28952*29*20533-2258~friends~(~(id~0~name~'Colon*20Salazar)~(id~1~name~'French*20Mcneil)~(id~2~name~'Carol*20Martin))~favoriteFruit~'banana)
QS: _id=5973782bdb9a930533b05cb2&isActive=true&balance=$1,446.35&age=32&name=Logan Keller&email=logankeller#artiq.com&phone=+1 (952) 533-2258&friends[0][id]=0&friends[0][name]=Colon Salazar&friends[1][id]=1&friends[1][name]=French Mcneil&friends[2][id]=2&friends[2][name]=Carol Martin&favoriteFruit=banana
URLON: $_id=5973782bdb9a930533b05cb2&isActive:true&balance=$1,446.35&age:32&name=Logan%20Keller&email=logankeller#artiq.com&phone=+1%20(952)%20533-2258&friends#$id:0&name=Colon%20Salazar;&$id:1&name=French%20Mcneil;&$id:2&name=Carol%20Martin;;&favoriteFruit=banana
QS-JSON: isActive=true&balance=%241%2C446.35&age=32&name=Logan+Keller&email=logankeller%40artiq.com&phone=%2B1+(952)+533-2258&friends(0).id=0&friends(0).name=Colon+Salazar&friends(1).id=1&friends(1).name=French+Mcneil&friends(2).id=2&friends(2).name=Carol+Martin&favoriteFruit=banana
The shortest among them is URL Object Notation.
There another popular library, qs. You can add it by:
yarn add qs
And then use it like this:
import qs from 'qs'
const array = { a: { b: 'c' } }
const stringified = qs.stringify(array, { encode: false })
console.log(stringified) //-- outputs a[b]=c
ES6 solution for query string encoding of a JavaScript object
const params = {
a: 1,
b: 'query stringify',
c: null,
d: undefined,
f: '',
g: { foo: 1, bar: 2 },
h: ['Winterfell', 'Westeros', 'Braavos'],
i: { first: { second: { third: 3 }}}
}
static toQueryString(params = {}, prefix) {
const query = Object.keys(params).map((k) => {
let key = k;
const value = params[key];
if (!value && (value === null || value === undefined || isNaN(value))) {
value = '';
}
switch (params.constructor) {
case Array:
key = `${prefix}[]`;
break;
case Object:
key = (prefix ? `${prefix}[${key}]` : key);
break;
}
if (typeof value === 'object') {
return this.toQueryString(value, key); // for nested objects
}
return `${key}=${encodeURIComponent(value)}`;
});
return query.join('&');
}
toQueryString(params)
"a=1&b=query%20stringify&c=&d=&f=&g[foo]=1&g[bar]=2&h[]=Winterfell&h[]=Westeros&h[]=Braavos&i[first][second][third]=3"
A single line to convert an object into a query string in case somebody needs it again:
let Objs = { a: 'obejct-a', b: 'object-b' }
Object.keys(objs).map(key => key + '=' + objs[key]).join('&')
// The result will be a=object-a&b=object-b
This is an addition for the accepted solution. This works with objects and array of objects:
parseJsonAsQueryString = function (obj, prefix, objName) {
var str = [];
for (var p in obj) {
if (obj.hasOwnProperty(p)) {
var v = obj[p];
if (typeof v == "object") {
var k = (objName ? objName + '.' : '') + (prefix ? prefix + "[" + p + "]" : p);
str.push(parseJsonAsQueryString(v, k));
} else {
var k = (objName ? objName + '.' : '') + (prefix ? prefix + '.' + p : p);
str.push(encodeURIComponent(k) + "=" + encodeURIComponent(v));
//str.push(k + "=" + v);
}
}
}
return str.join("&");
}
Also I have added objName if you're using object parameters, like in ASP.NET MVC action methods.
If you want to convert a nested object recursively and the object may or may not contain arrays (and the arrays may contain objects or arrays, etc), then the solution gets a little more complex. This is my attempt.
I've also added some options to choose if you want to record for each object member at what depth in the main object it sits, and to choose if you want to add a label to the members that come from converted arrays.
Ideally you should test if the thing parameter really receives an object or array.
function thingToString(thing,maxDepth,recordLevel,markArrays){
//thing: object or array to be recursively serialized
//maxDepth (int or false):
// (int) how deep to go with converting objects/arrays within objs/arrays
// (false) no limit to recursive objects/arrays within objects/arrays
//recordLevel (boolean):
// true - insert "(level 1)" before transcript of members at level one (etc)
// false - just
//markArrays (boolean):
// insert text to indicate any members that came from arrays
var result = "";
if (maxDepth !== false && typeof maxDepth != 'number') {maxDepth = 3;}
var runningDepth = 0;//Keeps track how deep we're into recursion
//First prepare the function, so that it can call itself recursively
function serializeAnything(thing){
//Set path-finder values
runningDepth += 1;
if(recordLevel){result += "(level " + runningDepth + ")";}
//First convert any arrays to object so they can be processed
if (thing instanceof Array){
var realObj = {};var key;
if (markArrays) {realObj['type'] = "converted array";}
for (var i = 0;i < thing.length;i++){
if (markArrays) {key = "a" + i;} else {key = i;}
realObj[key] = thing[i];
}
thing = realObj;
console.log('converted one array to ' + typeof realObj);
console.log(thing);
}
//Then deal with it
for (var member in thing){
if (typeof thing[member] == 'object' && runningDepth < maxDepth){
serializeAnything(thing[member]);
//When a sub-object/array is serialized, it will add one to
//running depth. But when we continue to this object/array's
//next sibling, the level must go back up by one
runningDepth -= 1;
} else if (maxDepth !== false && runningDepth >= maxDepth) {
console.log('Reached bottom');
} else
if (
typeof thing[member] == "string" ||
typeof thing[member] == 'boolean' ||
typeof thing[member] == 'number'
){
result += "(" + member + ": " + thing[member] + ") ";
} else {
result += "(" + member + ": [" + typeof thing[member] + " not supported]) ";
}
}
}
//Actually kick off the serialization
serializeAnything(thing);
return result;
}
This is a solution that will work for .NET backends out of the box. I have taken the primary answer of this thread and updated it to fit our .NET needs.
function objectToQuerystring(params) {
var result = '';
function convertJsonToQueryString(data, progress, name) {
name = name || '';
progress = progress || '';
if (typeof data === 'object') {
Object.keys(data).forEach(function (key) {
var value = data[key];
if (name == '') {
convertJsonToQueryString(value, progress, key);
} else {
if (isNaN(parseInt(key))) {
convertJsonToQueryString(value, progress, name + '.' + key);
} else {
convertJsonToQueryString(value, progress, name + '[' + key+ ']');
}
}
})
} else {
result = result ? result.concat('&') : result.concat('?');
result = result.concat(`${name}=${data}`);
}
}
convertJsonToQueryString(params);
return result;
}
To do it in a better way.
It can handle recursive objects or arrays in the standard query form, like a=val&b[0]=val&b[1]=val&c=val&d[some key]=val. Here's the final function.
Logic, Functionality
const objectToQueryString = (initialObj) => {
const reducer = (obj, parentPrefix = null) => (prev, key) => {
const val = obj[key];
key = encodeURIComponent(key);
const prefix = parentPrefix ? `${parentPrefix}[${key}]` : key;
if (val == null || typeof val === 'function') {
prev.push(`${prefix}=`);
return prev;
}
if (['number', 'boolean', 'string'].includes(typeof val)) {
prev.push(`${prefix}=${encodeURIComponent(val)}`);
return prev;
}
prev.push(Object.keys(val).reduce(reducer(val, prefix), []).join('&'));
return prev;
};
return Object.keys(initialObj).reduce(reducer(initialObj), []).join('&');
};
Example
const testCase1 = {
name: 'Full Name',
age: 30
}
const testCase2 = {
name: 'Full Name',
age: 30,
children: [
{name: 'Child foo'},
{name: 'Foo again'}
],
wife: {
name: 'Very Difficult to say here'
}
}
console.log(objectToQueryString(testCase1));
console.log(objectToQueryString(testCase2));
Live Test
Expand the snippet below to verify the result in your browser -
const objectToQueryString = (initialObj) => {
const reducer = (obj, parentPrefix = null) => (prev, key) => {
const val = obj[key];
key = encodeURIComponent(key);
const prefix = parentPrefix ? `${parentPrefix}[${key}]` : key;
if (val == null || typeof val === 'function') {
prev.push(`${prefix}=`);
return prev;
}
if (['number', 'boolean', 'string'].includes(typeof val)) {
prev.push(`${prefix}=${encodeURIComponent(val)}`);
return prev;
}
prev.push(Object.keys(val).reduce(reducer(val, prefix), []).join('&'));
return prev;
};
return Object.keys(initialObj).reduce(reducer(initialObj), []).join('&');
};
const testCase1 = {
name: 'Full Name',
age: 30
}
const testCase2 = {
name: 'Full Name',
age: 30,
children: [
{name: 'Child foo'},
{name: 'Foo again'}
],
wife: {
name: 'Very Difficult to say here'
}
}
console.log(objectToQueryString(testCase1));
console.log(objectToQueryString(testCase2));
Things to consider.
It skips values for functions, null, and undefined
It skips keys and values for empty objects and arrays.
It doesn't handle Number or String objects made with new Number(1) or new String('my string') because no one should ever do that
ok, it's a older post but i'm facing this problem and i have found my personal solution.. maybe can help someone else..
function objToQueryString(obj){
var k = Object.keys(obj);
var s = "";
for(var i=0;i<k.length;i++) {
s += k[i] + "=" + encodeURIComponent(obj[k[i]]);
if (i != k.length -1) s += "&";
}
return s;
};
URLSearchParams looks good, but it didn't work for nested objects.
Try to use
encodeURIComponent(JSON.stringify(object))
The previous answers do not work if you have a lot of nested objects.
Instead you can pick the function parameter from jquery-param/jquery-param.js. It worked very well for me!
var param = function (a) {
var s = [], rbracket = /\[\]$/,
isArray = function (obj) {
return Object.prototype.toString.call(obj) === '[object Array]';
}, add = function (k, v) {
v = typeof v === 'function' ? v() : v === null ? '' : v === undefined ? '' : v;
s[s.length] = encodeURIComponent(k) + '=' + encodeURIComponent(v);
}, buildParams = function (prefix, obj) {
var i, len, key;
if (prefix) {
if (isArray(obj)) {
for (i = 0, len = obj.length; i < len; i++) {
if (rbracket.test(prefix)) {
add(prefix, obj[i]);
} else {
buildParams(prefix + '[' + (typeof obj[i] === 'object' ? i : '') + ']', obj[i]);
}
}
} else if (obj && String(obj) === '[object Object]') {
for (key in obj) {
buildParams(prefix + '[' + key + ']', obj[key]);
}
} else {
add(prefix, obj);
}
} else if (isArray(obj)) {
for (i = 0, len = obj.length; i < len; i++) {
add(obj[i].name, obj[i].value);
}
} else {
for (key in obj) {
buildParams(key, obj[key]);
}
}
return s;
};
return buildParams('', a).join('&').replace(/%20/g, '+');
};
After going through some top answers here, I have wrote another implementation that tackles some edge cases as well
function serialize(params, prefix) {
return Object.entries(params).reduce((acc, [key, value]) => {
// remove whitespace from both sides of the key before encoding
key = encodeURIComponent(key.trim());
if (params.constructor === Array ) {
key = `${prefix}[]`;
} else if (params.constructor === Object) {
key = (prefix ? `${prefix}[${key}]` : key);
}
/**
* - undefined and NaN values will be skipped automatically
* - value will be empty string for functions and null
* - nested arrays will be flattened
*/
if (value === null || typeof value === 'function') {
acc.push(`${key}=`);
} else if (typeof value === 'object') {
acc = acc.concat(serialize(value, key));
} else if(['number', 'boolean', 'string'].includes(typeof value) && value === value) { // self-check to avoid NaN
acc.push(`${key}=${encodeURIComponent(value)}`);
}
return acc;
}, []);
}
function objectToQueryString(queryParameters) {
return queryParameters ? serialize(queryParameters).join('&'): '';
}
let x = objectToQueryString({
foo: 'hello world',
bar: {
blah: 123,
list: [1, 2, 3],
'nested array': [[4,5],[6,7]] // will be flattened
},
page: 1,
limit: undefined, // field will be ignored
check: false,
max: NaN, // field will be ignored
prop: null,
' key value': 'with spaces' // space in key will be trimmed out
});
console.log(x); // foo=hello%20world&bar[blah]=123&bar[list][]=1&bar[list][]=2&bar[list][]=3&bar[nested%20array][][]=4&bar[nested%20array][][]=5&bar[nested%20array][][]=6&bar[nested%20array][][]=7&page=1&check=false&prop=&key%20value=with%20spaces
Experimenting with an idea. Given an object like:
T = {
a: 2,
b: 9,
c: {
a: 3,
d: 6,
e: {
f: 12
}
}
}
I want to mutate it such that every value that is an object, changes to the same object, with the parent object as prototype.
Meaning I'd like to be able to have the following outputs:
> T.c.b
9
> T.c.e.b
9
> T.c.e.a
3
> T.c.c.c
{a: 3, d: 6, e:[Object]}
I have already created the following functions that work almost as expected:
function chainer(object) {
for (const key in object) {
if (object[key] !== null && typeof (object[key]) === 'object') {
let Constructor = function () {
};
Constructor.prototype = object;
let objectValue = {...object[key]};
object[key] = new Constructor();
for (const savedKey in objectValue) {
object[key][savedKey] = objectValue[savedKey];
}
}
}
}
function chain(object) {
chainer(object);
for (const key in object) {
if (object[key] !== null && typeof (object[key]) === 'object') {
chainer(object[key]);
}
}
}
With the previous example it works as expected. Nevertheless, when I try with the following:
T = {a:4, g:{g:{g:{g:{g:{g:{g:{}}}}}}}}
The following output happens:
> T.a
4
> T.g.a
4
> T.g.g.a
4
> T.g.g.g.a
undefined
> T.g.g.g.g.a
undefined
I find it weird it only works up to a point, it makes me think perhaps its an issue with some limit I'm not aware.
Anyway, I'm getting dizzy and out of ideas, any thoughts?
This seems to work fine:
ouroboros = (x, parent = null) => {
if (!x || typeof x !== 'object')
return x;
let r = Object.create(parent);
Object.entries(x).forEach(([k, v]) => r[k] = ouroboros(v, r));
return r;
};
//
T = ouroboros({x: 4, a: {b: {c: {d: {e: {}}}}}});
console.log(T.a.b.c.a.b.c.a.b.c.a.b.c.a.b.c.x);
or, mutating objects, instead of copying:
ouroboros = (x, parent = null) => {
if (x && typeof x === 'object') {
Object.setPrototypeOf(x, parent);
Object.values(x).forEach(v => ouroboros(v, x));
}
};
If I am not mistaking you wanted to do something like this:
rec = function (o) {
return Object.keys(o).reduce((acc, key) => {
if (typeof acc[key] === "object") {
const kv = {...rec(acc[key]), ...o}
return {...acc, ...kv, get [key]() { return this}}
}
return acc;
},o)
}
With an array, a value, and and an object with nested objects:
Object
mesh
Array
['options', 'range', 'x']
Value
12.5
Is it possible to translate this to update a property, e.g.
mesh.options.range.x = 12.5
Attempted:
index = (obj, i) ->
obj[i]
arr.reduce(index, obj) = 12.5
Update
Thank you all for the elegant solutions.
Using .reduce() is actually pretty nice for this:
// current object----| |----current key
// v v
arr.reduce(function(obj, key) {
return obj == null ? obj : obj[key];
}, window.mesh);
// ^
// |-- initial object
Your attempt to use .reduce() needed to pass a function that manages the "accumulation".
Here, as long as the previous obj wasn't null or undefined, it'll return the key of the current obj, which becomes the next obj.
Then since you need to assign a value, you'd actually want to get the value of the second to last key.
var o = arr.slice(0,-1).reduce(function(obj, key) {
return obj == null ? obj : obj[key];
}, window.mesh);
And then check its existence and use the last item in arr to do the assignment.
o && o[arr.pop()] = 12.5;
All of this can be abstracted away into a function that does one or the other based on how many arguments were passed.
function setFromArray(obj, arr, val) {
var keys = arguments.length < 3 ? arr.slice() : arr.slice(0, -1);
var o = keys.slice(0,-1).reduce(function(obj, key) {
return obj == null ? obj : obj[key];
}, window.mesh);
if (arguments.length < 3)
return o;
else
o && o[keys.pop()];
}
Here's a general solution:
function setPropertyPath(obj, path, value) {
var o = obj;
for (var i = 0; i < path.length - 1; i++) {
o = o[path[i]];
}
o[path[path.length - 1]] = value;
}
Usage:
var obj = { a: { b: { c: 0 } } };
setPropertyPath(obj, ['a', 'b', 'c'], 10);
console.log(obj.a.b.c); // prints '10'
JSBin
var mesh = {},
arr = ['options','range','x'],
value = 12.5;
mesh[arr[0]][arr[1]][arr[2]] = value;
If array length is static do something like this:
mesh[array[0]][array[1]][array[2]] = value;
However, one problem with this is that javascript doesn't do autovivification, so if you're accessing a key value that isn't previously defined you could run into errors (if mesh.options hasn't been defined then the above will throw an error because you can't assign to it). To solve that you might abstract this out into a function that handles things recursively:
http://jsfiddle.net/h4jVg/
function update_val(obj, array, val, prev) {
if (array.length == 0) {
obj = val;
return;
}
var cur = array.shift();
if(array.length == 0) {
obj[cur] = val;
return;
} else if (obj[cur] == undefined) {
obj[cur] = {};
}
update_val(obj[cur], array, val);
}
Is there a fast and simple way to encode a JavaScript object into a string that I can pass via a GET request?
No jQuery, no other frameworks—just plain JavaScript :)
Like this:
serialize = function(obj) {
var str = [];
for (var p in obj)
if (obj.hasOwnProperty(p)) {
str.push(encodeURIComponent(p) + "=" + encodeURIComponent(obj[p]));
}
return str.join("&");
}
console.log(serialize({
foo: "hi there",
bar: "100%"
}));
// foo=hi%20there&bar=100%25
This one also converts recursive objects (using PHP "array" notation for the query string):
serialize = function(obj, prefix) {
var str = [],
p;
for (p in obj) {
if (obj.hasOwnProperty(p)) {
var k = prefix ? prefix + "[" + p + "]" : p,
v = obj[p];
str.push((v !== null && typeof v === "object") ?
serialize(v, k) :
encodeURIComponent(k) + "=" + encodeURIComponent(v));
}
}
return str.join("&");
}
console.log(serialize({
foo: "hi there",
bar: {
blah: 123,
quux: [1, 2, 3]
}
}));
// foo=hi%20there&bar%5Bblah%5D=123&bar%5Bquux%5D%5B0%5D=1&bar%5Bquux%5D%5B1%5D=2&bar%5Bquux%5D%5B2%5D=3
Just use URLSearchParams This works in all current browsers
new URLSearchParams(object).toString()
jQuery has a function for this, jQuery.param(). If you're already using it, you can use this:
Example:
var params = { width:1680, height:1050 };
var str = jQuery.param( params );
str now contains width=1680&height=1050.
I suggest using the URLSearchParams interface:
const searchParams = new URLSearchParams();
const params = {foo: "hi there", bar: "100%" };
Object.keys(params).forEach(key => searchParams.append(key, params[key]));
console.log(searchParams.toString())
Or by passing the search object into the constructor like this:
const params = {foo: "hi there", bar: "100%" };
const queryString = new URLSearchParams(params).toString();
console.log(queryString);
Use:
Object.keys(obj).reduce(function(a,k){a.push(k+'='+encodeURIComponent(obj[k]));return a},[]).join('&')
I like this one-liner, but I bet it would be a more popular answer if it matched the accepted answer semantically:
function serialize( obj ) {
let str = '?' + Object.keys(obj).reduce(function(a, k){
a.push(k + '=' + encodeURIComponent(obj[k]));
return a;
}, []).join('&');
return str;
}
Here's a one liner in ES6:
Object.keys(obj).map(k => `${encodeURIComponent(k)}=${encodeURIComponent(obj[k])}`).join('&');
With Node.js v6.6.3
const querystring = require('querystring')
const obj = {
foo: 'bar',
baz: 'tor'
}
let result = querystring.stringify(obj)
// foo=bar&baz=tor
Reference: Query string
Ruby on Rails and PHP style query builder
This method converts a JavaScript object into a URI query string. It also handles nested arrays and objects (in Ruby on Rails and PHP syntax):
function serializeQuery(params, prefix) {
const query = Object.keys(params).map((key) => {
const value = params[key];
if (params.constructor === Array)
key = `${prefix}[]`;
else if (params.constructor === Object)
key = (prefix ? `${prefix}[${key}]` : key);
if (typeof value === 'object')
return serializeQuery(value, key);
else
return `${key}=${encodeURIComponent(value)}`;
});
return [].concat.apply([], query).join('&');
}
Example Usage:
let params = {
a: 100,
b: 'has spaces',
c: [1, 2, 3],
d: { x: 9, y: 8}
}
serializeQuery(params)
// returns 'a=100&b=has%20spaces&c[]=1&c[]=2&c[]=3&d[x]=9&d[y]=8
A small amendment to the accepted solution by user187291:
serialize = function(obj) {
var str = [];
for(var p in obj){
if (obj.hasOwnProperty(p)) {
str.push(encodeURIComponent(p) + "=" + encodeURIComponent(obj[p]));
}
}
return str.join("&");
}
Checking for hasOwnProperty on the object makes JSLint and JSHint happy, and it prevents accidentally serializing methods of the object or other stuff if the object is anything but a simple dictionary. See the paragraph on for statements on Code Conventions for the JavaScript Programming Language.
Well, everyone seems to put his one-liner here so here goes mine:
const encoded = Object.entries(obj).map(([k, v]) => `${k}=${encodeURIComponent(v)}`).join("&");
If you need to send arbitrary objects, then GET is a bad idea since there are limits to the lengths of URLs that user agents and web servers will accepts. My suggestion would be to build up an array of name-value pairs to send and then build up a query string:
function QueryStringBuilder() {
var nameValues = [];
this.add = function(name, value) {
nameValues.push( {name: name, value: value} );
};
this.toQueryString = function() {
var segments = [], nameValue;
for (var i = 0, len = nameValues.length; i < len; i++) {
nameValue = nameValues[i];
segments[i] = encodeURIComponent(nameValue.name) + "=" + encodeURIComponent(nameValue.value);
}
return segments.join("&");
};
}
var qsb = new QueryStringBuilder();
qsb.add("veg", "cabbage");
qsb.add("vegCount", "5");
alert( qsb.toQueryString() );
A little bit look better
objectToQueryString(obj, prefix) {
return Object.keys(obj).map(objKey => {
if (obj.hasOwnProperty(objKey)) {
const key = prefix ? `${prefix}[${objKey}]` : objKey;
const value = obj[objKey];
return typeof value === "object" ?
this.objectToQueryString(value, key) :
`${encodeURIComponent(key)}=${encodeURIComponent(value)}`;
}
return null;
}).join("&");
}
This one skips null/undefined values
export function urlEncodeQueryParams(data) {
const params = Object.keys(data).map(key => data[key] ? `${encodeURIComponent(key)}=${encodeURIComponent(data[key])}` : '');
return params.filter(value => !!value).join('&');
}
Here's the CoffeeScript version of the accepted answer.
serialize = (obj, prefix) ->
str = []
for p, v of obj
k = if prefix then prefix + "[" + p + "]" else p
if typeof v == "object"
str.push(serialize(v, k))
else
str.push(encodeURIComponent(k) + "=" + encodeURIComponent(v))
str.join("&")
Here's a concise & recursive version with Object.entries. It handles arbitrarily nested arrays, but not nested objects. It also removes empty elements:
const format = (k,v) => v !== null ? `${k}=${encodeURIComponent(v)}` : ''
const to_qs = (obj) => {
return [].concat(...Object.entries(obj)
.map(([k,v]) => Array.isArray(v)
? v.map(arr => to_qs({[k]:arr}))
: format(k,v)))
.filter(x => x)
.join('&');
}
E.g.:
let json = {
a: [1, 2, 3],
b: [], // omit b
c: 1,
d: "test&encoding", // uriencode
e: [[4,5],[6,7]], // flatten this
f: null, // omit nulls
g: 0
};
let qs = to_qs(json)
=> "a=1&a=2&a=3&c=1&d=test%26encoding&e=4&e=5&e=6&e=7&g=0"
Use:
const toQueryString = obj => "?".concat(Object.keys(obj).map(e => `${encodeURIComponent(e)}=${encodeURIComponent(obj[e])}`).join("&"));
const data = {
offset: 5,
limit: 10
};
toQueryString(data); // => ?offset=5&limit=10
Or use a predefined feature
const data = {
offset: 5,
limit: 10
};
new URLSearchParams(data).toString(); // => ?offset=5&limit=10
Note
Both the above methods will set the value as null if not present.
If you want not to set the query parameter if value is null then use:
const toQueryString = obj => "?".concat(Object.keys(obj).map(e => obj[e] ? `${encodeURIComponent(e)}=${encodeURIComponent(obj[e])}` : null).filter(e => !!e).join("&"));
const data = {
offset: null,
limit: 10
};
toQueryString(data); // => "?limit=10" else with above methods "?offset=null&limit=10"
You can freely use any method.
In ES7 you can write this in one line:
const serialize = (obj) => (Object.entries(obj).map(i => [i[0], encodeURIComponent(i[1])].join('=')).join('&'))
There another popular library, qs. You can add it by:
yarn add qs
And then use it like this:
import qs from 'qs'
const array = { a: { b: 'c' } }
const stringified = qs.stringify(array, { encode: false })
console.log(stringified) //-- outputs a[b]=c
I have a simpler solution that does not use any third-party library and is already apt to be used in any browser that has "Object.keys" (aka all modern browsers + edge + ie):
In ES5
function(a){
if( typeof(a) !== 'object' )
return '';
return `?${Object.keys(a).map(k=>`${k}=${a[k]}`).join('&')}`;
}
In ES3
function(a){
if( typeof(a) !== 'object' )
return '';
return '?' + Object.keys(a).map(function(k){ return k + '=' + a[k] }).join('&');
}
I made a comparison of JSON stringifiers and the results are as follows:
JSON: {"_id":"5973782bdb9a930533b05cb2","isActive":true,"balance":"$1,446.35","age":32,"name":"Logan Keller","email":"logankeller#artiq.com","phone":"+1 (952) 533-2258","friends":[{"id":0,"name":"Colon Salazar"},{"id":1,"name":"French Mcneil"},{"id":2,"name":"Carol Martin"}],"favoriteFruit":"banana"}
Rison: (_id:'5973782bdb9a930533b05cb2',age:32,balance:'$1,446.35',email:'logankeller#artiq.com',favoriteFruit:banana,friends:!((id:0,name:'Colon Salazar'),(id:1,name:'French Mcneil'),(id:2,name:'Carol Martin')),isActive:!t,name:'Logan Keller',phone:'+1 (952) 533-2258')
O-Rison: _id:'5973782bdb9a930533b05cb2',age:32,balance:'$1,446.35',email:'logankeller#artiq.com',favoriteFruit:banana,friends:!((id:0,name:'Colon Salazar'),(id:1,name:'French Mcneil'),(id:2,name:'Carol Martin')),isActive:!t,name:'Logan Keller',phone:'+1 (952) 533-2258'
JSURL: ~(_id~'5973782bdb9a930533b05cb2~isActive~true~balance~'!1*2c446.35~age~32~name~'Logan*20Keller~email~'logankeller*40artiq.com~phone~'*2b1*20*28952*29*20533-2258~friends~(~(id~0~name~'Colon*20Salazar)~(id~1~name~'French*20Mcneil)~(id~2~name~'Carol*20Martin))~favoriteFruit~'banana)
QS: _id=5973782bdb9a930533b05cb2&isActive=true&balance=$1,446.35&age=32&name=Logan Keller&email=logankeller#artiq.com&phone=+1 (952) 533-2258&friends[0][id]=0&friends[0][name]=Colon Salazar&friends[1][id]=1&friends[1][name]=French Mcneil&friends[2][id]=2&friends[2][name]=Carol Martin&favoriteFruit=banana
URLON: $_id=5973782bdb9a930533b05cb2&isActive:true&balance=$1,446.35&age:32&name=Logan%20Keller&email=logankeller#artiq.com&phone=+1%20(952)%20533-2258&friends#$id:0&name=Colon%20Salazar;&$id:1&name=French%20Mcneil;&$id:2&name=Carol%20Martin;;&favoriteFruit=banana
QS-JSON: isActive=true&balance=%241%2C446.35&age=32&name=Logan+Keller&email=logankeller%40artiq.com&phone=%2B1+(952)+533-2258&friends(0).id=0&friends(0).name=Colon+Salazar&friends(1).id=1&friends(1).name=French+Mcneil&friends(2).id=2&friends(2).name=Carol+Martin&favoriteFruit=banana
The shortest among them is URL Object Notation.
ES6 solution for query string encoding of a JavaScript object
const params = {
a: 1,
b: 'query stringify',
c: null,
d: undefined,
f: '',
g: { foo: 1, bar: 2 },
h: ['Winterfell', 'Westeros', 'Braavos'],
i: { first: { second: { third: 3 }}}
}
static toQueryString(params = {}, prefix) {
const query = Object.keys(params).map((k) => {
let key = k;
const value = params[key];
if (!value && (value === null || value === undefined || isNaN(value))) {
value = '';
}
switch (params.constructor) {
case Array:
key = `${prefix}[]`;
break;
case Object:
key = (prefix ? `${prefix}[${key}]` : key);
break;
}
if (typeof value === 'object') {
return this.toQueryString(value, key); // for nested objects
}
return `${key}=${encodeURIComponent(value)}`;
});
return query.join('&');
}
toQueryString(params)
"a=1&b=query%20stringify&c=&d=&f=&g[foo]=1&g[bar]=2&h[]=Winterfell&h[]=Westeros&h[]=Braavos&i[first][second][third]=3"
A single line to convert an object into a query string in case somebody needs it again:
let Objs = { a: 'obejct-a', b: 'object-b' }
Object.keys(objs).map(key => key + '=' + objs[key]).join('&')
// The result will be a=object-a&b=object-b
This is an addition for the accepted solution. This works with objects and array of objects:
parseJsonAsQueryString = function (obj, prefix, objName) {
var str = [];
for (var p in obj) {
if (obj.hasOwnProperty(p)) {
var v = obj[p];
if (typeof v == "object") {
var k = (objName ? objName + '.' : '') + (prefix ? prefix + "[" + p + "]" : p);
str.push(parseJsonAsQueryString(v, k));
} else {
var k = (objName ? objName + '.' : '') + (prefix ? prefix + '.' + p : p);
str.push(encodeURIComponent(k) + "=" + encodeURIComponent(v));
//str.push(k + "=" + v);
}
}
}
return str.join("&");
}
Also I have added objName if you're using object parameters, like in ASP.NET MVC action methods.
If you want to convert a nested object recursively and the object may or may not contain arrays (and the arrays may contain objects or arrays, etc), then the solution gets a little more complex. This is my attempt.
I've also added some options to choose if you want to record for each object member at what depth in the main object it sits, and to choose if you want to add a label to the members that come from converted arrays.
Ideally you should test if the thing parameter really receives an object or array.
function thingToString(thing,maxDepth,recordLevel,markArrays){
//thing: object or array to be recursively serialized
//maxDepth (int or false):
// (int) how deep to go with converting objects/arrays within objs/arrays
// (false) no limit to recursive objects/arrays within objects/arrays
//recordLevel (boolean):
// true - insert "(level 1)" before transcript of members at level one (etc)
// false - just
//markArrays (boolean):
// insert text to indicate any members that came from arrays
var result = "";
if (maxDepth !== false && typeof maxDepth != 'number') {maxDepth = 3;}
var runningDepth = 0;//Keeps track how deep we're into recursion
//First prepare the function, so that it can call itself recursively
function serializeAnything(thing){
//Set path-finder values
runningDepth += 1;
if(recordLevel){result += "(level " + runningDepth + ")";}
//First convert any arrays to object so they can be processed
if (thing instanceof Array){
var realObj = {};var key;
if (markArrays) {realObj['type'] = "converted array";}
for (var i = 0;i < thing.length;i++){
if (markArrays) {key = "a" + i;} else {key = i;}
realObj[key] = thing[i];
}
thing = realObj;
console.log('converted one array to ' + typeof realObj);
console.log(thing);
}
//Then deal with it
for (var member in thing){
if (typeof thing[member] == 'object' && runningDepth < maxDepth){
serializeAnything(thing[member]);
//When a sub-object/array is serialized, it will add one to
//running depth. But when we continue to this object/array's
//next sibling, the level must go back up by one
runningDepth -= 1;
} else if (maxDepth !== false && runningDepth >= maxDepth) {
console.log('Reached bottom');
} else
if (
typeof thing[member] == "string" ||
typeof thing[member] == 'boolean' ||
typeof thing[member] == 'number'
){
result += "(" + member + ": " + thing[member] + ") ";
} else {
result += "(" + member + ": [" + typeof thing[member] + " not supported]) ";
}
}
}
//Actually kick off the serialization
serializeAnything(thing);
return result;
}
This is a solution that will work for .NET backends out of the box. I have taken the primary answer of this thread and updated it to fit our .NET needs.
function objectToQuerystring(params) {
var result = '';
function convertJsonToQueryString(data, progress, name) {
name = name || '';
progress = progress || '';
if (typeof data === 'object') {
Object.keys(data).forEach(function (key) {
var value = data[key];
if (name == '') {
convertJsonToQueryString(value, progress, key);
} else {
if (isNaN(parseInt(key))) {
convertJsonToQueryString(value, progress, name + '.' + key);
} else {
convertJsonToQueryString(value, progress, name + '[' + key+ ']');
}
}
})
} else {
result = result ? result.concat('&') : result.concat('?');
result = result.concat(`${name}=${data}`);
}
}
convertJsonToQueryString(params);
return result;
}
To do it in a better way.
It can handle recursive objects or arrays in the standard query form, like a=val&b[0]=val&b[1]=val&c=val&d[some key]=val. Here's the final function.
Logic, Functionality
const objectToQueryString = (initialObj) => {
const reducer = (obj, parentPrefix = null) => (prev, key) => {
const val = obj[key];
key = encodeURIComponent(key);
const prefix = parentPrefix ? `${parentPrefix}[${key}]` : key;
if (val == null || typeof val === 'function') {
prev.push(`${prefix}=`);
return prev;
}
if (['number', 'boolean', 'string'].includes(typeof val)) {
prev.push(`${prefix}=${encodeURIComponent(val)}`);
return prev;
}
prev.push(Object.keys(val).reduce(reducer(val, prefix), []).join('&'));
return prev;
};
return Object.keys(initialObj).reduce(reducer(initialObj), []).join('&');
};
Example
const testCase1 = {
name: 'Full Name',
age: 30
}
const testCase2 = {
name: 'Full Name',
age: 30,
children: [
{name: 'Child foo'},
{name: 'Foo again'}
],
wife: {
name: 'Very Difficult to say here'
}
}
console.log(objectToQueryString(testCase1));
console.log(objectToQueryString(testCase2));
Live Test
Expand the snippet below to verify the result in your browser -
const objectToQueryString = (initialObj) => {
const reducer = (obj, parentPrefix = null) => (prev, key) => {
const val = obj[key];
key = encodeURIComponent(key);
const prefix = parentPrefix ? `${parentPrefix}[${key}]` : key;
if (val == null || typeof val === 'function') {
prev.push(`${prefix}=`);
return prev;
}
if (['number', 'boolean', 'string'].includes(typeof val)) {
prev.push(`${prefix}=${encodeURIComponent(val)}`);
return prev;
}
prev.push(Object.keys(val).reduce(reducer(val, prefix), []).join('&'));
return prev;
};
return Object.keys(initialObj).reduce(reducer(initialObj), []).join('&');
};
const testCase1 = {
name: 'Full Name',
age: 30
}
const testCase2 = {
name: 'Full Name',
age: 30,
children: [
{name: 'Child foo'},
{name: 'Foo again'}
],
wife: {
name: 'Very Difficult to say here'
}
}
console.log(objectToQueryString(testCase1));
console.log(objectToQueryString(testCase2));
Things to consider.
It skips values for functions, null, and undefined
It skips keys and values for empty objects and arrays.
It doesn't handle Number or String objects made with new Number(1) or new String('my string') because no one should ever do that
ok, it's a older post but i'm facing this problem and i have found my personal solution.. maybe can help someone else..
function objToQueryString(obj){
var k = Object.keys(obj);
var s = "";
for(var i=0;i<k.length;i++) {
s += k[i] + "=" + encodeURIComponent(obj[k[i]]);
if (i != k.length -1) s += "&";
}
return s;
};
URLSearchParams looks good, but it didn't work for nested objects.
Try to use
encodeURIComponent(JSON.stringify(object))
The previous answers do not work if you have a lot of nested objects.
Instead you can pick the function parameter from jquery-param/jquery-param.js. It worked very well for me!
var param = function (a) {
var s = [], rbracket = /\[\]$/,
isArray = function (obj) {
return Object.prototype.toString.call(obj) === '[object Array]';
}, add = function (k, v) {
v = typeof v === 'function' ? v() : v === null ? '' : v === undefined ? '' : v;
s[s.length] = encodeURIComponent(k) + '=' + encodeURIComponent(v);
}, buildParams = function (prefix, obj) {
var i, len, key;
if (prefix) {
if (isArray(obj)) {
for (i = 0, len = obj.length; i < len; i++) {
if (rbracket.test(prefix)) {
add(prefix, obj[i]);
} else {
buildParams(prefix + '[' + (typeof obj[i] === 'object' ? i : '') + ']', obj[i]);
}
}
} else if (obj && String(obj) === '[object Object]') {
for (key in obj) {
buildParams(prefix + '[' + key + ']', obj[key]);
}
} else {
add(prefix, obj);
}
} else if (isArray(obj)) {
for (i = 0, len = obj.length; i < len; i++) {
add(obj[i].name, obj[i].value);
}
} else {
for (key in obj) {
buildParams(key, obj[key]);
}
}
return s;
};
return buildParams('', a).join('&').replace(/%20/g, '+');
};
After going through some top answers here, I have wrote another implementation that tackles some edge cases as well
function serialize(params, prefix) {
return Object.entries(params).reduce((acc, [key, value]) => {
// remove whitespace from both sides of the key before encoding
key = encodeURIComponent(key.trim());
if (params.constructor === Array ) {
key = `${prefix}[]`;
} else if (params.constructor === Object) {
key = (prefix ? `${prefix}[${key}]` : key);
}
/**
* - undefined and NaN values will be skipped automatically
* - value will be empty string for functions and null
* - nested arrays will be flattened
*/
if (value === null || typeof value === 'function') {
acc.push(`${key}=`);
} else if (typeof value === 'object') {
acc = acc.concat(serialize(value, key));
} else if(['number', 'boolean', 'string'].includes(typeof value) && value === value) { // self-check to avoid NaN
acc.push(`${key}=${encodeURIComponent(value)}`);
}
return acc;
}, []);
}
function objectToQueryString(queryParameters) {
return queryParameters ? serialize(queryParameters).join('&'): '';
}
let x = objectToQueryString({
foo: 'hello world',
bar: {
blah: 123,
list: [1, 2, 3],
'nested array': [[4,5],[6,7]] // will be flattened
},
page: 1,
limit: undefined, // field will be ignored
check: false,
max: NaN, // field will be ignored
prop: null,
' key value': 'with spaces' // space in key will be trimmed out
});
console.log(x); // foo=hello%20world&bar[blah]=123&bar[list][]=1&bar[list][]=2&bar[list][]=3&bar[nested%20array][][]=4&bar[nested%20array][][]=5&bar[nested%20array][][]=6&bar[nested%20array][][]=7&page=1&check=false&prop=&key%20value=with%20spaces