I want to search all the elemetns of a Javascript object and replace every occurance of the text "???" with, say for example, "***".
An example of the JSON would be
{
"page-title": "Tasks",
"sections": [{
"section-heading": "Work",
"subsections": [{
"subsection-heading": "First",
"subsection-texts": [{
"text": "This is some text."
}]
}, {
"subsection-heading": "Second",
"subsection-texts": [{
"text": "This is some more text."
}, {
"text": "This is even more text ???."
}]
}, {
"subsection-heading": "Third ???",
"subsection-texts": [{
"text": "This is the last text."
}]
}]
}]
}
As you can see, the "???" text could be at different levels. So is there some way of searching and replacing every occurance of $???$ with "***"?
I am looking for a method that will check the actual JSON object elements, I do not want a method that stringifys the object and then uses regex. Can this be done efficiently?
You can iterate through all object properties or array items with map/reduce and replace all question marks for strings:
var data = { ... }
function replaceQuestionMarks(obj) {
if (Array.isArray(obj)) {
return obj.map(function(o) {
return replaceQuestionMarks(o);
})
} else if (typeof obj === 'object') {
return Object.keys(obj).reduce(function(r, key) {
r[key] = replaceQuestionMarks(obj[key]);
return r;
}, {})
} else if (typeof obj === 'string') {
return obj.replace('???', '***');
}
return obj;
}
var replaced = replaceQuestionMarks(data);
One approach would be to convert it to a string, replace the question marks with a regular expression and then parse back into an object:
var myObject = {...};
myObject = (JSON.parse(JSON.stringify(myObject).replace(/\?\?\?/gi, '***')));
This might not be the best way to do it in terms of performance but we'd need more details about what you are actually doing. This may be just as efficient as other ways of doing it. How big are the objects on which you need to do this?
Related
I want to fetch all the names and label from JSON without loop. Is there a way to fetch with any filter method?
"sections": [
{
"id": "62ee1779",
"name": "Drinks",
"items": [
{
"id": "1902b625",
"name": "Cold Brew",
"optionSets": [
{
"id": "45f2a845-c83b-49c2-90ae-a227dfb7c513",
"label": "Choose a size",
},
{
"id": "af171c34-4ca8-4374-82bf-a418396e375c",
"label": "Additional Toppings",
},
],
},
]
}
When you say "without loops" I take it as without For Loops. because any kind of traversal of arrays, let alone nested traversal, involve iterating.
You can use the reduce method to have it done for you internally and give you the format you need.
Try this :
const data = {
sections: [
{
id: "62ee1779",
name: "Drinks",
items: [
{
id: "1902b625",
name: "Cold Brew",
optionSets: [
{
id: "45f2a845-c83b-49c2-90ae-a227dfb7c513",
label: "Choose a size"
},
{
id: "af171c34-4ca8-4374-82bf-a418396e375c",
label: "Additional Toppings"
}
]
}
]
}
]
};
x = data.sections.reduce((acc, ele) => {
acc.push(ele.name);
otherName = ele.items.reduce((acc2, elem2) => {
acc2.push(elem2.name);
label = elem2.optionSets.reduce((acc3, elem3) => {
acc3.push(elem3.label);
return acc3;
}, []);
return acc2.concat(label);
}, []);
return acc.concat(otherName);
}, []);
console.log(x);
Go ahead and press run snippet to see if this matches your desired output.
For More on info reduce method
In the context of cJSON
yes, we can fetch the key value for any of the object.
1 - each key value is pointed by one of the objects. will simply fetch that object and from there will get the key value.
In the above case for
pre-requisition: root must contain the json format and root must be the cJSON pointer. if not we can define it and use cJSON_Parse() to parse the json.
1st name object is "sections" will use
cJSON *test = cJSON_GetObjectItem(root, "sections");
char *name1 = cJSON_GetObjectItem(test, "name" )->valuestring;
2nd name key value
cJSON *test2 = cJSON_GetObjectItem(test, "items");
char *name2 = cJSON_GetObjectItem(tes2, "name")->valuestring;
likewise, we can do for others as well to fetch the key value.
I would like to be able to type in "Hammerhead" to call the "Hammerhead Shark" object without its full name. Is this possible and if so how?
I tried using array.indexOf(string) though it doesn't really seem to help since it requires an exact match such as typing "Hammerhead Shark"
JS:
const JSON = require('animals.json');
var animals = Object.keys(JSON);
if (animals.indexOf("Hammerhead")) {
console.log(JSON["Hammerhead"].name);
}
JSON:
{
"Hammerhead Shark": {
"name": "Shark",
"age": "300"
},
"Duck": {
"name": "Duck",
"age": "1000"
}
}
I expect the output to be "Shark" instead of undefined.
It seems you want to get access the value in object. By its partial name.
Get the entries of object using Object.entries()
Find the key which includes() the given partial key.
return the second element of the found entry.
const obj = { "Hammerhead Shark": { "name": "Shark", "age": "300" }, "Duck": { "name": "Duck", "age": "1000" } }
function getValueByPartialKey(obj,key){
return (Object.entries(obj).find(([k,v]) => k.includes(key)) || [])[1]
}
console.log(getValueByPartialKey(obj,"Hammerhead"))
You can use string.includes(word) to return the name that matches the string that you're searching for, along with Array.filter iterates over the values too, and returns the result(s) you want.
I have a response from a web service and want to replace some values in the response with my custom values.
One way is to write a tree traverser and then check for the value and replace with my custom value
so the response is some what like this:
[
{
"name": "n1",
"value": "v1",
"children": [
{
"name": "n2",
"value": "v2"
}
]
},
{
"name": "n3",
"value": "v3"
}
]
now my custom map is like this
const map = {
"v1": "v11",
"v2": "v22",
"v3": "v33"
};
All I want is
[
{
"name": "n1",
"value": "v11",
"children": [
{
"name": "n2",
"value": "v22"
}
]
},
{
"name": "n3",
"value": "v33"
}
]
I was thinking if I could stringify my response and then replace values using a custom build regex from my map of values.
Will it be faster as compared to tree traverser?
If yes, how should I do that?
somewhat like this
originalString.replace(regexp, function (replacement))
The tree traversal is faster
Note that some things could be done more efficiently in the regex implementation but I still think there are some more bottlenecks to explain.
Why the regex is slow:
There are probably many more reasons why the regex is slower but I'll explain at least one significant reason:
When you're using regex to find and replace, you're using creating new strings every time and performing your matches every time. Regex expressions can be very expensive and my implementation isn't particularly cheap.
Why is the tree traversal faster:
In the tree traversal, I'm mutating the object directly. This doesn't require creating new string objects or any new objects at all. We're also not performing a full search on the whole string every time as well.
RESULTS
run the performance test below. The test using console.time to record how long it takes. See the the tree traversal is much faster.
function usingRegex(obj, map) {
return JSON.parse(Object.keys(map).map(oldValue => ({
oldValue,
newValue: map[oldValue]
})).reduce((json, {
oldValue,
newValue
}) => {
return json.replace(
new RegExp(`"value":"(${oldValue})"`),
() => `"value":"${newValue}"`
);
}, JSON.stringify(obj)));
}
function usingTree(obj, map) {
function traverse(children) {
for (let item of children) {
if (item && item.value) {
// get a value from a JS object is O(1)!
item.value = map[item.value];
}
if (item && item.children) {
traverse(item.children)
}
}
}
traverse(obj);
return obj; // mutates
}
const obj = JSON.parse(`[
{
"name": "n1",
"value": "v1",
"children": [
{
"name": "n2",
"value": "v2"
}
]
},
{
"name": "n3",
"value": "v3"
}
]`);
const map = {
"v1": "v11",
"v2": "v22",
"v3": "v33"
};
// show that each function is working first
console.log('== TEST THE FUNCTIONS ==');
console.log('usingRegex', usingRegex(obj, map));
console.log('usingTree', usingTree(obj, map));
const iterations = 10000; // ten thousand
console.log('== DO 10000 ITERATIONS ==');
console.time('regex implementation');
for (let i = 0; i < iterations; i += 1) {
usingRegex(obj, map);
}
console.timeEnd('regex implementation');
console.time('tree implementation');
for (let i = 0; i < iterations; i += 1) {
usingTree(obj, map);
}
console.timeEnd('tree implementation');
Will it be faster as compared to tree traverser?
I don't know. I think it would depend on the size of the input, and the size of the replacement map. You could run some tests at JSPerf.com.
If yes, how should I do that?
It's fairly easy to do with a regex-based string replacement if the values you are replacing don't need any special escaping or whatever. Something like this:
const input = [
{
"name": "n1",
"value": "v1",
"children": [
{
"name": "n2",
"value": "v2"
}
]
},
{
"name": "n3",
"value": "v3"
}
];
const map = {
"v1": "v11",
"v2": "v22",
"v3": "v33"
};
// create a regex that matches any of the map keys, adding ':' and quotes
// to be sure to match whole property values and not property names
const regex = new RegExp(':\\s*"(' + Object.keys(map).join('|') + ')"', 'g');
// NOTE: if you've received this data as JSON then do the replacement
// *before* parsing it, don't parse it then restringify it then reparse it.
const json = JSON.stringify(input);
const result = JSON.parse(
json.replace(regex, function(m, key) { return ': "' + map[key] + '"'; })
);
console.log(result);
definitely traverser go faster as string replace means travels against each characters in the final string as opposed to iterator that can skips no necessarily item.
I have the following JSON:
{
"responseObject": {
"name": "ObjectName",
"fields": [
{
"fieldName": "refId",
"value": "2170gga35511"
},
{
"fieldName": "telNum",
"value": "4541885881"
}]}
}
I want to access "value" of the the array element with "fieldName": "telNum" without using index numbers, because I don't know everytime exactly at which place this telNum element will appear.
What I dream of is something like this:
jsonVarName.responseObject.fields['fieldname'='telNum'].value
Is this even possible in JavaScript?
You can do it like this
var k={
"responseObject": {
"name": "ObjectName",
"fields": [
{
"fieldName": "refId",
"value": "2170gga35511"
},
{
"fieldName": "telNum",
"value": "4541885881"
}]
}};
value1=k.responseObject.fields.find(
function(i)
{return (i.fieldName=="telNum")}).value;
console.log(value1);
There is JSONPath that lets you write queries just like XPATH does for XML.
$.store.book[*].author the authors of all books in the store
$..author all authors
$.store.* all things in store, which are some books and a red bicycle.
$.store..price the price of everything in the store.
$..book[2] the third book
$..book[(#.length-1)]
$..book[-1:] the last book in order.
$..book[0,1]
$..book[:2] the first two books
$..book[?(#.isbn)] filter all books with isbn number
$..book[?(#.price<10)] filter all books cheapier than 10
$..* All members of JSON structure.
You will have to loop through and find it.
var json = {
"responseObject": {
"name": "ObjectName",
"fields": [
{
"fieldName": "refId",
"value": "2170gga35511"
},
{
"fieldName": "telNum",
"value": "4541885881"
}]
};
function getValueForFieldName(fieldName){
for(var i=0;i<json.fields.length;i++){
if(json.fields[i].fieldName == fieldName){
return json.fields[i].value;
}
}
return false;
}
console.log(getValueForFieldName("telNum"));
It might be a better option to modify the array into object with fieldName as keys once to avoid using .find over and over again.
fields = Object.assign({}, ...fields.map(field => {
const newField = {};
newField[field.fieldName] = field.value;
return newField;
}
It's not possible.. Native JavaScript has nothing similar to XPATH like in xml to iterate through JSON. You have to loop or use Array.prototype.find() as stated in comments.
It's experimental and supported only Chrome 45+, Safari 7.1+, FF 25+. No IE.
Example can be found here
Clean and easy way to just loop through array.
var json = {
"responseObject": {
"name": "ObjectName",
"fields": [
{
"fieldName": "refId",
"value": "2170gga35511"
},
{
"fieldName": "telNum",
"value": "4541885881"
}]
}
$(json.responseObject.fields).each(function (i, field) {
if (field.fieldName === "telNum") {
return field.value // break each
}
})
I am using AngularJS. I have a json object as below;
info = [
{
"name": "Tom",
"id": "111"
},
{
"name": "Sam",
"id": "222"
},
{
"name": "James",
"id": "333"
}
]
I want to have a function such that when a matching name is found, some action is taken (in this -case, return the corresponding id.) In other words, if the input matching name is 'Tom', I want to return the id '111' based on the json object above.
I wrote some code to find a matching name.
$scope.getIdFromName = function()
{
angular.forEach(info, function(value, key)
{
//$scope.searchByName contains the name to be matched
if (key === 'name' && value === $scope.searchByName)
{
//$scope.searchById is the id to be returned
$scope.searchById = key;
alert("found");
}
});
};
Where did the code go wrong? Or is it so wrong that it is better to be completely rewritten? Any suggestions (does not need to be angularjs) will be most welcome. Thank you very much.
Since info is an array of objects, the key is going to be the index of each item, and value will be the whole object at that index. Your forEach should look like this:
angular.forEach(info, function(value, key)
{
//$scope.searchByName contains the name to be matched
if (value.name === $scope.searchByName)
{
//$scope.searchById is the id to be returned
$scope.searchById = value.id;
alert("found");
}
});