Create an object from an array of keys and an array of values

Question

I have two arrays: newParamArr and paramVal.

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

Example values in the paramVal array: [ "Jon", 15, "jon@gmail.com" ].

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], ... }.

In this case, the result should be { Name: "Jon", "Age": 15, "Email": "jon@gmail.com" }.

The lengths of the two arrays are always the same, but the length of arrays can increase or decrease. That means newParamArr.length === paramVal.length will always hold.

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

Answer 1

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

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

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.

Answer 2

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]}))

Answer 3

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} 

Answer 4

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]} ) ) );

Answer 5

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];
}

console.log(obj);

Answer 6

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

Answer 7

Object.fromEntries takes an array of key, value tuples and return the zipped result as object, you can then use it as follow:

    const keys = ["a","b","c"];
    const values = [1,2,3];
    Object.fromEntries(keys.map((key, index)=> [key, values[index]])); // {a: 1, b: 2, c: 3}
    

Answer 8

Use a loop:

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

Answer 9

This one works for me.

    var keys = ['foo', 'bar', 'baz'];
    var values = [11, 22, 33]
    var result = {};
    keys.forEach(function(key, i){result[key] = values[i]});
    console.log(result);