How to store two arrays as a keyvalue pair in one object in JavaScript?

Suppose, we have two arrays of literals of same length like these ?

const arr1 = ['firstName', 'lastName', 'age', 'address', 'isEmployed'];
const arr2 = ['Rahul', 'Sharma', 23, 'Tilak Nagar', false];

We are required to write a JavaScript function that takes in two such arrays.

The function should construct an object mapping the elements of the second array to the corresponding elements of the first array.

Method 1: Using Array.reduce()

We will use the Array.prototype.reduce() method to iterate over the arrays, building the object.

const arr1 = ['firstName', 'lastName', 'age', 'address', 'isEmployed'];
const arr2 = ['Rahul', 'Sharma', 23, 'Tilak Nagar', false];

const mapArrays = (arr1 = [], arr2 = []) => {
    const res = arr1.reduce((acc, elem, index) => {
        acc[elem] = arr2[index];
        return acc;
    }, {});
    return res;
};

console.log(mapArrays(arr1, arr2));

{
  firstName: 'Rahul',
  lastName: 'Sharma',
  age: 23,
  address: 'Tilak Nagar',
  isEmployed: false
}

Method 2: Using Object.fromEntries() with Array.map()

A more concise approach using modern JavaScript methods:

const arr1 = ['firstName', 'lastName', 'age', 'address', 'isEmployed'];
const arr2 = ['Rahul', 'Sharma', 23, 'Tilak Nagar', false];

const mapArraysModern = (keys, values) => {
    return Object.fromEntries(keys.map((key, index) => [key, values[index]]));
};

console.log(mapArraysModern(arr1, arr2));

{
  firstName: 'Rahul',
  lastName: 'Sharma',
  age: 23,
  address: 'Tilak Nagar',
  isEmployed: false
}

Method 3: Using a Simple for Loop

For better performance with large arrays, use a traditional loop:

const arr1 = ['firstName', 'lastName', 'age', 'address', 'isEmployed'];
const arr2 = ['Rahul', 'Sharma', 23, 'Tilak Nagar', false];

const mapArraysLoop = (keys, values) => {
    const result = {};
    for (let i = 0; i 

{
  firstName: 'Rahul',
  lastName: 'Sharma',
  age: 23,
  address: 'Tilak Nagar',
  isEmployed: false
}


Comparison

Conclusion

Use Object.fromEntries() for modern, readable code. For maximum compatibility or performance with large datasets, use the for loop approach. Array.reduce() offers a good balance between readability and compatibility.