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I want to return an array of objects without any duplicate ids. If there are any, then take the first one we see. So, we should NOT see {id: "2", value: '10'}. Instead, the value should be "Italian". I have this code below, but I am getting an map.has is not a function error.
const arr1 = [{
id: "1",
value: "English"
},
{
id: "2",
value: "Italian"
}
];
const arr2 = [{
id: "2",
value: '10'
},
{
id: "3",
value: "German"
}
];
const concatArr = arr1.concat(arr2);
const mergedArr = [...concatArr.reduce((map, obj) => map.has(obj.id) ? "" : map.set(obj.id, obj), new Map()).values()];
console.log(mergedArr);
You need to always return a map not an empty string when the thing is already in the map.
const arr1 = [{
id: "1",
value: "English"
},
{
id: "2",
value: "Italian"
}
];
const arr2 = [{
id: "2",
value: '10'
},
{
id: "3",
value: "German"
}
];
const concatArr = arr1.concat(arr2);
const mergedArr = [...concatArr.reduce((map, obj) => map.has(obj.id) ? map : map.set(obj.id, obj), new Map()).values()];
console.log(mergedArr);
You can use array#reduce to uniquely identify each object with unique id in an object accumulator and then extract all values from this object using Object.values().
const arr1 = [{ id: "1", value: "English" }, { id: "2", value: "Italian" } ],
arr2 = [{ id: "2", value: '10' }, { id: "3", value: "German" } ],
result = Object.values(arr1.concat(arr2).reduce((r, o) => {
r[o.id] = r[o.id] || o;
return r;
},{}));
console.log(result);
I have an array of objects with the same keys, example:
const data = [{name: "firstName", value: "John"},
{name: "lastName", value: "Smith"},
{name: "Number", value: "421-8686"}
]
I however want the values to become the key and values. example:
const data = [{"firstName": "John"},
{"lastName": "Smith"},
{"Number": "421-8686"}]
I tried a few methods, but for some reason or another I fail. My latest attempt is:
let newData = {}
arrayData.forEach((item, index) => {
let key = data.name
let value = data.value
newData[index] = { key: value} // this results in {"key": "John"} --> but i want {"firstName": "John"}
});
You can use Object.fromEntries.
let data = [
{name: "firstName", value: "John"},
{name: "lastName", value: "Smith"},
{name: "Number", value: "421-8686"}
]
data = data.map(info => Object.fromEntries([[info.name, info.value]]))
console.log(data)
const data = [{name: "firstName", value: "John"},
{name: "lastName", value: "Smith"},
{name: "Number", value: "421-8686"}
]
/*const data = [{"firstName": "John"},
{"lastName": "Smith"},
{"Number": "421-8686"}]
*/
for(let i = 0;i < data.length;i++){
data[i][data[i].name] = data[i].value // creates new key value pair
delete data[i].name // deletes old key
delete data[i].value
}
console.log(data)
let data = [
{ name: "firstName", value: "John" },
{ name: "lastName", value: "Smith" },
{ name: "Number", value: "421-8686" },
];
// map the data to required format.
data = data.map((d) => {
let o = {};
o[d["name"]] = d["value"];
return o;
});
console.log("data",data);
I believe you should get result as following, what you want.
Of course, I confirmed status.
const data = [{name: "firstName", value: "John"},
{name: "lastName", value: "Smith"},
{name: "Number", value: "421-8686"}
]
let newData = [];
data.forEach((item) => {
let obj = {};
obj[item.name] = item.value;
newData.push( obj );
});
console.log(newData);
Thanks.
Just a small tweak to your code. Property has to be dynamically created.
In ES6, we can dynamically create a property key by placing the key in square brackets [].
const data = [
{ name: "firstName", value: "John" },
{ name: "lastName", value: "Smith" },
{ name: "Number", value: "421-8686" }
];
let newData = [];
data.forEach((item, index) => newData[index] = {[item.name]: item.value});
console.log(newData)
This question already has answers here:
How do I convert array of Objects into one Object in JavaScript?
(17 answers)
Closed 1 year ago.
I have an array of objects with key-value pair, how to convert it to an object by reducing it to a single object by removing keys. I tried with map filter reduce but couldn't get the desired result. please help
const object = Object.assign({}, ...obj); // not working
const result = {};
Object.keys(object).forEach((key, index) => {
result[`newObj${index + 1}`] = obj[key].map(item => ({[key]: item}));
}); // not working
Input
obj = [{key: name, value: jack},{key: age, value: 10},{key: country, value: india},{key: state, value: Delhi}];
Output
{name:jack, age:10, country:india, state: Delhi}
Use forEach and destructuring
Update: Fixed based on Jan pointed out. Thanks #Jan
obj = [
{ key: "name", value: "jack" },
{ key: "age", value: 10 },
{ key: "country", value: "india" },
{ key: "state", value: "Delhi" },
];
const res = {};
obj.forEach(({ key, value }) => Object.assign(res, { [key]: value }));
console.log(res);
Alternatively, use Object.fromEntries and map
obj = [
{ key: "name", value: "jack" },
{ key: "age", value: 10 },
{ key: "country", value: "india" },
{ key: "state", value: "Delhi" },
];
const res = Object.fromEntries(obj.map(Object.values));
console.log(res);
var obj=[{key: "name", value: "jack"},{key: "age", value: 10},{key: "country", value: "india"},{key: "state", value: "Delhi"}]
var myObj={};
for (var item of obj){
myObj[item.key]=item.value
}
console.log(myObj)
will output
{name: "jack", age: 10, country: "india", state: "Delhi"}
You can use reduce for this:
var input = [
{key: "name", value: "jack"},
{key: "age", value: 10},
{key: "country", value: "India"},
{key: "state", value: "Delhi"},
]
var output = input.reduce((r,{key,value}) => ({[key]:value,...r}),{})
console.log(output)
Output
{ state: 'Delhi', country: 'India', age: 10, name: 'jack' }
The solution uses
object destructuring {key,value}
object spread syntax {...r}
object computed property names {[key]:value}
I think you want like this...
var obj = [
{key: "name", value: "jack"},
{key: "age", value: 10},
{key: "country", value: "india"},
{key: "state", value: "Delhi"}
];
let tempObject = {};
for (let c of obj) {
tempObject[c.key]= c.value;
}
console.log(tempObject);
I have an array which looks something like below:
[
{
name: "ReceiverId",
value: "1"
},
{name: "TransSequence", value: "KPJ7dL2pmx0njInNRAzUug"},
{
name: "email-address",
value: "xcv#cvb.com"
},
{
name: "mobile-number",
value: "9321313213"
},
{
name: "ReceiverId",
value: "2"
},
{
name: "TransSequence",
value: "KPJ7dL2pmx0njInNRAzUug"
},
{
name: "email-address",
value: "xcv#cvb.com"
}
]
Now I want to make my json data looks like this:
{
"MainData": [
{
"TransSequence": "wpiuVJw",
"ReceiverId": "1",
"ReceiverEmail": "xcv#cvb.com",
"ReceiverMobileNo": "9321313213",
},
{
"TransSequence": "xowpiuVJw",
"ReceiverId": "2",
"ReceiverEmail": "xcv#cvb.com",
"ReceiverMobileNo": "9321313213",
}
]
}
However I tried below code snippet:
mArr = []
obj = {};
for(var i=0; i<mainArr.length; i++){
// obj = {};
for(j = 0; j < 4; j++){
obj[mainArr[i].name] = mainArr[i].value
}
}
But above code snippet returns the last values only. However, I have also tried to convert into string based json but in last array it return as , which throws error while parsing it.
HELP WOULD BE APPRECIATED!!
Basing the code you tried, you are using js.
In js, you can use reduce to summarize the array. Use Object.assign to combine objects.
let arr = [{"name":"ReceiverId","value":"1"},{"name":"TransSequence","value":"KPJ7dL2pmx0njInNRAzUug"},{"name":"email-address","value":"xcv#cvb.com"},{"name":"mobile-number","value":"9321313213"},{"name":"ReceiverId","value":"2"},{"name":"TransSequence","value":"KPJ7dL2pmx0njInNRAzUug"},{"name":"email-address","value":"xcv#cvb.com"},{"name":"mobile-number","value":"9321231321"},{"name":"ReceiverId","value":"1"},{"name":"TransSequence","value":"KPJ7dL2pmx0njInNRAzUug"},{"name":"email-address","value":"xcv#cvb.com"},{"name":"mobile-number","value":"9321231321"},{"name":"ReceiverId","value":"2"}];
let propertyCount = 4;
let result = arr.reduce((c, v, i) => {
let o = Math.floor(i / propertyCount);
c[o] = c[o] || {};
c[o] = Object.assign(c[o], {[v.name]: v.value});
return c;
}, []);
console.log(result);
Here is my take:
const input = [
{name: "ReceiverId", value: "1"},
{name: "TransSequence", value: "KPJ7dL2pmx0njInNRAzUug"},
{name: "email-address", value: "xcv#cvb.com"},
{name: "mobile-number", value: "9321313213"},
{name: "ReceiverId", value: "2"},
{name: "TransSequence", value: "KPJ7dL2pmx0njInNRAzUug"},
{name: "email-address", value: "xcv#cvb.com"},
{name: "mobile-number", value: "9321231321"},
{name: "ReceiverId", value: "1"},
{name: "TransSequence", value: "KPJ7dL2pmx0njInNRAzUug"},
{name: "email-address", value: "xcv#cvb.com"},
{name: "mobile-number", value: "9321231321"},
{name: "ReceiverId", value: "2"}
];
let data = [];
input.forEach(e => {
// If it's a new data point, add it.
if (e.name === 'ReceiverId') {
data.push({
ReceiverId: e.value
})
// Add it to the last array.
} else {
data[data.length-1][e.name] = e.value
}
})
let output = {
MainData: data
}
// Your output
console.log(output)
.as-console-wrapper {min-height: 100%;}
Here is the correct code
let mainArr = [{"name":"ReceiverId","value":"1"},{"name":"TransSequence","value":"KPJ7dL2pmx0njInNRAzUug"},{"name":"email-address","value":"xcv#cvb.com"},{"name":"mobile-number","value":"9321313213"},{"name":"ReceiverId","value":"2"},{"name":"TransSequence","value":"KPJ7dL2pmx0njInNRAzUug"},{"name":"email-address","value":"xcv#cvb.com"},{"name":"mobile-number","value":"9321231321"},{"name":"ReceiverId","value":"1"},{"name":"TransSequence","value":"KPJ7dL2pmx0njInNRAzUug"},{"name":"email-address","value":"xcv#cvb.com"},{"name":"mobile-number","value":"9321231321"}];
const obj = {
MainData: [],
}
for(var i=0; i<mainArr.length / 4; i++){
const local = {}
for(j = i * 4; j < i * 4 + 4; j++){
local[mainArr[j].name] = mainArr[j].value
}
obj.MainData.push(local);
}
console.log(obj)
What is the best way to merge array contents from JavaScript objects sharing a key in common?
How can array in the example below be reorganized into output? Here, all value keys (whether an array or not) are merged into all objects sharing the same name key.
var array = [
{
name: "foo1",
value: "val1"
}, {
name: "foo1",
value: [
"val2",
"val3"
]
}, {
name: "foo2",
value: "val4"
}
];
var output = [
{
name: "foo1",
value: [
"val1",
"val2",
"val3"
]
}, {
name: "foo2",
value: [
"val4"
]
}
];
Here is one option:-
var array = [{
name: "foo1",
value: "val1"
}, {
name: "foo1",
value: ["val2", "val3"]
}, {
name: "foo2",
value: "val4"
}];
var output = [];
array.forEach(function(item) {
var existing = output.filter(function(v, i) {
return v.name == item.name;
});
if (existing.length) {
var existingIndex = output.indexOf(existing[0]);
output[existingIndex].value = output[existingIndex].value.concat(item.value);
} else {
if (typeof item.value == 'string')
item.value = [item.value];
output.push(item);
}
});
console.dir(output);
Here is another way of achieving that goal:
var array = [{
name: "foo1",
value: "val1"
}, {
name: "foo1",
value: [
"val2",
"val3"
]
}, {
name: "foo2",
value: "val4"
}];
var output = array.reduce(function(o, cur) {
// Get the index of the key-value pair.
var occurs = o.reduce(function(n, item, i) {
return (item.name === cur.name) ? i : n;
}, -1);
// If the name is found,
if (occurs >= 0) {
// append the current value to its list of values.
o[occurs].value = o[occurs].value.concat(cur.value);
// Otherwise,
} else {
// add the current item to o (but make sure the value is an array).
var obj = {
name: cur.name,
value: [cur.value]
};
o = o.concat([obj]);
}
return o;
}, []);
console.log(output);
2021 version
Using reduce to aggregate data.
Using logical nullish assignment only assigns if acc[name] is nullish (null or undefined).
Using Array.isArray to determines whether the passed value is an Array.
var arrays = [{ name: "foo1",value: "val1" }, {name: "foo1", value: ["val2", "val3"] }, {name: "foo2",value: "val4"}];
const result = arrays.reduce((acc, {name, value}) => {
acc[name] ??= {name: name, value: []};
if(Array.isArray(value)) // if it's array type then concat
acc[name].value = acc[name].value.concat(value);
else
acc[name].value.push(value);
return acc;
}, {});
console.log(Object.values(result));
Using lodash
var array = [{name:"foo1",value:"val1"},{name:"foo1",value:["val2","val3"]},{name:"foo2",value:"val4"}];
function mergeNames (arr) {
return _.chain(arr).groupBy('name').mapValues(function (v) {
return _.chain(v).pluck('value').flattenDeep();
}).value();
}
console.log(mergeNames(array));
Here is a version using an ES6 Map:
const arrays = [{ name: "foo1",value: "val1" }, {name: "foo1", value: ["val2", "val3"] }, {name: "foo2",value: "val4"}];
const map = new Map(arrays.map(({name, value}) => [name, { name, value: [] }]));
for (let {name, value} of arrays) map.get(name).value.push(...[value].flat());
console.log([...map.values()]);
Use lodash "uniqWith". As shown below
let _ = require("lodash");
var array = [
{ name: "foo1", value: "1" },
{ name: "foo1", value: "2" },
{ name: "foo2", value: "3" },
{ name: "foo1", value: "4" }
];
let merged = _.uniqWith(array, (pre, cur) => {
if (pre.name == cur.name) {
cur.value = cur.value + "," + pre.value;
return true;
}
return false;
});
console.log(merged);
// output: [{ name: "foo1", value: "1,2,4" }, { name: "foo2", value: "3" }];
Using reduce:
var mergedObj = array.reduce((acc, obj) => {
if (acc[obj.name]) {
acc[obj.name].value = acc[obj.name].value.isArray ?
acc[obj.name].value.concat(obj.value) :
[acc[obj.name].value].concat(obj.value);
} else {
acc[obj.name] = obj;
}
return acc;
}, {});
let output = [];
for (let prop in mergedObj) {
output.push(mergedObj[prop])
}
It's been a while since this question was asked, but I thought I'd chime in as well. For functions like this that execute a basic function you'll want to use over and over, I prefer to avoid longer-written functions and loops if I can help it and develop the function as a one-liner using shallow Array.prototype functions like .map() and some other ES6+ goodies like Object.entries() and Object.fromEntries(). Combining all these, we can execute a function like this relatively easily.
First, I take in however many objects you pass to the function as a rest parameter and prepend that with an empty object we'll use to collect all the keys and values.
[{}, ...objs]
Next, I use the .map() Array prototype function paired with Object.entries() to loop through all the entries of each object, and any sub-array elements each contains and then either set the empty object's key to that value if it has not yet been declared, or I push the new values to the object key if it has been declared.
[{},...objs].map((e,i,a) => i ? Object.entries(e).map(f => (a[0][f[0]] ? a[0][f[0]].push(...([f[1]].flat())) : (a[0][f[0]] = [f[1]].flat()))) : e)[0]
Finally, to replace any single-element-arrays with their contained value, I run another .map() function on the result array using both Object.entries() and Object.fromEntries(), similar to how we did before.
let getMergedObjs = (...objs) => Object.fromEntries(Object.entries([{},...objs].map((e,i,a) => i ? Object.entries(e).map(f => (a[0][f[0]] ? a[0][f[0]].push(...([f[1]].flat())) : (a[0][f[0]] = [f[1]].flat()))) : e)[0]).map(e => e.map((f,i) => i ? (f.length > 1 ? f : f[0]) : f)));
This will leave you with the final merged object, exactly as you prescribed it.
let a = {
a: [1,9],
b: 1,
c: 1
}
let b = {
a: 2,
b: 2
}
let c = {
b: 3,
c: 3,
d: 5
}
let getMergedObjs = (...objs) => Object.fromEntries(Object.entries([{},...objs].map((e,i,a) => i ? Object.entries(e).map(f => (a[0][f[0]] ? a[0][f[0]].push(...([f[1]].flat())) : (a[0][f[0]] = [f[1]].flat()))) : e)[0]).map(e => e.map((f,i) => i ? (f.length > 1 ? f : f[0]) : f)));
getMergedObjs(a,b,c); // { a: [ 1, 9, 2 ], b: [ 1, 2, 3 ], c: [ 1, 3 ], d: 5 }
Try this:
var array = [{name:"foo1",value:"val1"},{name:"foo1",value:["val2","val3"]},{name:"foo2",value:"val4"},{name:"foo2",value:"val5"}];
for(var j=0;j<array.length;j++){
var current = array[j];
for(var i=j+1;i<array.length;i++){
if(current.name = array[i].name){
if(!isArray(current.value))
current.value = [ current.value ];
if(isArray(array[i].value))
for(var v=0;v<array[i].value.length;v++)
current.value.push(array[i].value[v]);
else
current.value.push(array[i].value);
array.splice(i,1);
i++;
}
}
}
function isArray(myArray) {
return myArray.constructor.toString().indexOf("Array") > -1;
}
document.write(JSON.stringify(array));
This work too !
var array = [
{
name: "foo1",
value: "val1",
},
{
name: "foo1",
value: ["val2", "val3"],
},
{
name: "foo2",
value: "val4",
},
];
let arr2 = [];
array.forEach((element) => { // remove duplicate name
let match = arr2.find((r) => r.name == element.name);
if (match) {
} else {
arr2.push({ name: element.name, value: [] });
}
});
arr2.map((item) => {
array.map((e) => {
if (e.name == item.name) {
if (typeof e.value == "object") { //lets map if value is an object
e.value.map((z) => {
item.value.push(z);
});
} else {
item.value.push(e.value);
}
}
});
});
console.log(arr2);
const exampleObj = [{
year: 2016,
abd: 123
}, {
year: 2016,
abdc: 123
}, {
year: 2017,
abdcxc: 123
}, {
year: 2017,
abdcxcx: 123
}];
const listOfYears = [];
const finalObj = [];
exampleObj.map(sample => {
listOfYears.push(sample.year);
});
const uniqueList = [...new Set(listOfYears)];
uniqueList.map(list => {
finalObj.push({
year: list
});
});
exampleObj.map(sample => {
const sampleYear = sample.year;
finalObj.map((obj, index) => {
if (obj.year === sampleYear) {
finalObj[index] = Object.assign(sample, obj);
}
});
});
The final object be [{"year":2016,"abdc":123,"abd":123},{"year":2017,"abdcxcx":123,"abdcxc":123}]
const array = [{ name: "foo1", value: "val1" }, {name: "foo1", value: ["val2", "val3"] }, {name: "foo2", value: "val4"}];
const start = array.reduce((object, {name}) => ({...object, [name]: []}), {});
const result = array.reduce((object, {name, value}) => ({...object, [name]: [object[name], [value]].flat(2)}), start);
const output = Object.entries(result).map(([name, value]) => ({name: name, value: value}));
console.log(output);
try this :
var array = [
{
name: "foo1",
value: "val1"
}, {
name: "foo1",
value: [
"val2",
"val3"
]
}, {
name: "foo2",
value: "val4"
}
];
var output = [
{
name: "foo1",
value: [
"val1",
"val2",
"val3"
]
}, {
name: "foo2",
value: [
"val4"
]
}
];
bb = Object.assign( {}, array, output );
console.log(bb) ;
A much more easier approach is this 2022:
var array = [
{
name: "foo1",
value: "val1"
}, {
name: "foo1",
value: [
"val2",
"val3"
]
}, {
name: "foo2",
value: "val4"
}
];
var output = [
{
name: "foo1",
value: [
"val1",
"val2",
"val3"
]
},
{
name: "foo2",
value: [
"val4"
]
}
];
function mergeBasedOnKey(list){
let c = Object.values(list.reduce((a, b) => {
a[b.name] = a[b.name] || {name: b.name, value: []}
if(typeof(b['value']) == "string"){
a[b.name].value.push(b['value'])
}
else{
a[b.name].value = [...a[b.name].value, ...b.value]
}
return a
}, {}))
return c
}
let ans = mergeBasedOnKey(array)
console.log(ans)
I was looking for a quick, almost "one-liner" answer in this thread, provided that this is a trivial but common exercise.
I couldn't find any for my like. The other answers are fine but I am not much into boilerplate.
So, let me add one, then:
o = array.reduce((m,{name:n,value:v})=>({...m,[n]:[...m[n]||[],v].flat(1)}),{})
output = Object.entries(o).map(([n,v])=>({name:n,value:v}))
var array = [
{ name: "foo1", value: "val1"},
{ name: "foo1", value: ["val2","val3"] },
{ name: "foo2", value: "val4" }
]
o=array.reduce((m,{name:n,value:v})=>({...m,[n]:[...m[n]||[],v].flat(1)}),{})
output=Object.entries(o).map(([n,v])=>({name:n,value:v}))
console.log(output)