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Creating a JavaScript Object from two arrays

Posted by: admin February 22, 2020 Leave a comment


I have two arrays: newParamArr[i] and paramVal[i].

Example values in the newParamArr[i] array:
["Name", "Age", "Email"]

Example values in the paramVal[i] array:
["Jon", "15", "[email protected]"]

I need to create a JavaScript object that places all of the items in the array in the same object. For example

{newParamArr[0]:paramVal[0], newParamArr[1]:paramVal[1], ...}

The lengths of the two arrays are always the same, but the length of arrays can increase or decrease. As in…

newParamArr.length === paramVal.length will always returns true.

None of the below posts could help to answer my question:

Javascript Recursion for creating a JSON object

Recursively looping through an object to build a property list

How to&Answer:

Do you mean this?

var keys = ['foo', 'bar', 'baz'];
var values = [11, 22, 33]

var result = {};
keys.forEach((key, i) => result[key] = values[i]);

Alternatively, you can use Object.assign

result = Object.assign(...keys.map((k, i) => ({[k]: values[i]})))

or the object spread syntax (ES2018):

result = keys.reduce((o, k, i) => ({...o, [k]: values[i]}), {})

or Object.fromEntries (ES2019):

Object.fromEntries(keys.map((_, i) => [keys[i], values[i]]))

In case you’re using lodash, there’s _.zipObject exactly for this type of thing.


Using ECMAScript2015:

const obj = newParamArr.reduce((obj, value, index) => {
    obj[value] = paramArr[index];
    return obj;
}, {});

(EDIT) Previously misunderstood the OP to want an array:

const arr = newParamArr.map((value, index) => ({[value]: paramArr[index]}))


The following worked for me.

//test arrays
var newParamArr = [1, 2, 3, 4, 5];
var paramVal = ["one", "two", "three", "four", "five"];

//create an empty object to ensure it's the right type.
var obj = {};

//loop through the arrays using the first one's length since they're the same length
for(var i = 0; i < newParamArr.length; i++)
    //set the keys and values
    //avoid dot notation for the key in this case
    //use square brackets to set the key to the value of the array element
    obj[newParamArr[i]] = paramVal[i];



I know that the question is already a year old, but here is a one-line solution:

Object.assign( ...newParamArr.map( (v, i) => ( {[v]: paramVal[i]} ) ) );


You can use Object.assign.apply() to merge an array of {key:value} pairs into the object you want to create:

Object.assign.apply({}, keys.map( (v, i) => ( {[v]: values[i]} ) ) )

A runnable snippet:

var keys = ['foo', 'bar', 'baz'];
var values = [11, 22, 33]

var result =  Object.assign.apply({}, keys.map( (v, i) => ( {[v]: values[i]} ) ) );
console.log(result); //returns {"foo": 11, "bar": 22, "baz": 33}

See the documentation for more


Use a loop:

var result = {};
for (var i = 0; i < newParamArr.length; i++) {
  result[newParamArr[i]] = paramArr[i];


I needed this in a few places so I made this function…

function zip(arr1,arr2,out={}){
    arr1.map( (val,idx)=>{ out[val] = arr2[idx]; } );
    return out;

console.log( zip( ["a","b","c"], [1,2,3] ) );

> {'a': 1, 'b': 2, 'c': 3} 


You can do this using javascript ES 6 new feature :

For example :

var keys = ['zahid', 'fahim', 'hasib' ,'iftakhar'];

var ages = [11, 22, 33 ,31];

var testObject = {
    [keys.shift()] : ages.shift(),
    [keys.shift()] : ages.shift(),
    [keys.shift()] : ages.shift(),
    [keys.shift()] : ages.shift()


console.log(testObject); // { zahid: 11, fahim: 22, hasib: 33, iftakhar: 31 }