How to Store Key-Value Array in JavaScript

  1. Use JavaScript Object to Store a Key-Value Array
  2. Use JavaScript Map to Store a Key-Value Array

Arrays in JavaScript are single variables storing different elements. We could need them to store a list of elements, and each element has an index to access them by it. JavaScript has different methods to store a key-value array.

Use JavaScript Object to Store a Key-Value Array

The JavaScript Object is an entity with properties, and each property has value, so key-value terminology can work on it.

Example:

let obj1 = { id: 1, name: 'Mark', age: 30, country: "USA" };
obj1.city = "New York";
obj1['job'] = "software developer";

console.log(obj1);

Output:

{
age: 30
city: "New York"
country: "USA"
id: 1
job: "software developer"
name: "Mark"
}

We can loop through it:

let obj1 = { id: 1, name: 'Mark', age: 30, country: "USA" };
obj1.city = "New York";
obj1['job'] = "software developer";

for (let key in obj1) {
  console.log(key + " => " + obj1[key]);
}

Output:

id => 1
name => Mark
age => 30
country => USA
city => New York
job => software developer

If we have an array, we can loop through the array one by one, add the keys from each element’s index, and the corresponding values in the Object.

let arr1 = ["delfstack", "Computer", "Science"]; 

let obj1 = {}; 

for(let i = 0; i < arr1.length; i++){ 
  obj1[i] = arr1[i]; 
} 

for (let key of Object.keys(obj1)) { 
  console.log(key + " => " + obj1[key] ) 
} 

Output:

0 => delfstack
1 => Computer
2 => Science

Use JavaScript Map to Store a Key-Value Array

Map is just like an Object. It is a list of keyed data items. The difference is that Map allows any type of keys.

Syntax of JavaScript Map

let map = new Map();
  • Store key => value:
map.set('name', 'mark'); 

Example of Java Map

let arr1 = ["delfstack", "Computer", "Science"]; 

let map = new Map(); 

for(let i = 0; i < arr1.length; i++){ 
  map.set(i, arr1[i]); 
} 

for (let key of map.keys()) { 
  console.log(key + " => " + map.get(key) ) 
} 

Output:

0 => delfstack
1 => Computer
2 => Science

Related Article - JavaScript Array

  • How to Compare Two Arrays in JavaScript
  • Related Article - JavaScript Map

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  • How to Empty an Array in JavaScript