How to Convert an Array of Key-Value Pairs to a Map in JavaScript - Step by Step Examples

How to Convert an Array of Key-Value Pairs to a Map in JavaScript ?

Answer

To convert an array of key-value pairs to a map in JavaScript, you can iterate over the array and insert each key-value pair into the map. This method allows you to create a map from a collection of key-value pairs stored in an array.

✐ Examples

1 Converting an Array of Arrays to a Map

We can convert an array of key-value pairs to a map in JavaScript by iterating over the array and adding each key-value pair to the map.

For example,

We start by declaring and initializing an array of key-value pairs named pairs. In this example, the pairs are represented as arrays with two elements: a key and a value.
We declare an empty map named myMap to store the key-value pairs.
We iterate over the array using the forEach method and add each pair to the map.
We print the resulting map to the console using the console.log function to verify the conversion.

JavaScript Program

const pairs = [
    [1, 10],
    [2, 20],
    [3, 30],
    [4, 40],
    [5, 50]
];

// Declare an empty map to store the key-value pairs
const myMap = new Map();

// Iterate over the array and add each pair to the map
pairs.forEach(([key, value]) => {
    myMap.set(key, value);
});

// Print the resulting map
console.log('Map from array of pairs:');
myMap.forEach((value, key) => {
    console.log(`${key}: ${value}`);
});

Output

Map from array of pairs:
1: 10
2: 20
3: 30
4: 40
5: 50

2 Converting an Array of Objects to a Map

We can convert an array of objects with key and value properties to a map in JavaScript by iterating over the array and adding each object's key-value pair to the map.

For example,

We start by declaring and initializing an array of objects named pairs. In this example, each object has key and value properties.
We declare an empty map named myMap to store the key-value pairs.
We iterate over the array using the forEach method and add each object's key-value pair to the map.
We print the resulting map to the console using the console.log function to verify the conversion.

JavaScript Program

const pairs = [
    { key: 1, value: 10 },
    { key: 2, value: 20 },
    { key: 3, value: 30 },
    { key: 4, value: 40 },
    { key: 5, value: 50 }
];

// Declare an empty map to store the key-value pairs
const myMap = new Map();

// Iterate over the array and add each object's key-value pair to the map
pairs.forEach(({ key, value }) => {
    myMap.set(key, value);
});

// Print the resulting map
console.log('Map from array of objects:');
myMap.forEach((value, key) => {
    console.log(`${key}: ${value}`);
});

Output

Map from array of objects:
1: 10
2: 20
3: 30
4: 40
5: 50

3 Converting a List of Pairs to a Map

We can convert a list of key-value pairs to a map in JavaScript by iterating over the list and adding each key-value pair to the map.

For example,

We start by declaring and initializing a list of key-value pairs named pairs. In this example, the pairs are represented as arrays with two elements: a key and a value.
We declare an empty map named myMap to store the key-value pairs.
We iterate over the list using the forEach method and add each pair to the map.
We print the resulting map to the console using the console.log function to verify the conversion.

JavaScript Program

const pairs = [
    [1, 10],
    [2, 20],
    [3, 30],
    [4, 40],
    [5, 50]
];

// Declare an empty map to store the key-value pairs
const myMap = new Map();

// Iterate over the list and add each pair to the map
pairs.forEach(([key, value]) => {
    myMap.set(key, value);
});

// Print the resulting map
console.log('Map from list of pairs:');
myMap.forEach((value, key) => {
    console.log(`${key}: ${value}`);
});

Output

Map from list of pairs:
1: 10
2: 20
3: 30
4: 40
5: 50

Summary

In this tutorial, we learned How to Convert an Array of Key-Value Pairs to a Map in JavaScript language with well detailed examples.

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How to Convert an Array of Key-Value Pairs to a Map in JavaScript - Step by Step Examples