How to Copy a Map in JavaScript

How to Copy a Map in JavaScript ?

Answer

To copy a map in JavaScript, you can use the Map constructor or the spread operator to create a new map with the same key-value pairs as the original map. These methods provide straightforward ways to duplicate a map.

✐ Examples

1 Copying a Map Using the Map Constructor

We can copy a map in JavaScript using the Map constructor, which creates a new map with the same key-value pairs as the original map.

For example,

We start by declaring and initializing a map named originalMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the Map constructor to create a new map named copiedMap that contains the same key-value pairs as originalMap.
We print the copied map to the console using the console.log function to verify the copy.

JavaScript Program

const originalMap = new Map([
    ['one', 1],
    ['two', 2],
    ['three', 3]
]);

// Copy the map using the Map constructor
const copiedMap = new Map(originalMap);

// Print the copied map
console.log('Copied Map:', Array.from(copiedMap));

Output

Copied Map: [['one', 1], ['two', 2], ['three', 3]]

2 Copying a Map Using the Spread Operator

We can also copy a map in JavaScript using the spread operator, which creates a new map with the same key-value pairs as the original map.

For example,

We start by declaring and initializing a map named originalMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the spread operator to create a new map named copiedMap that contains the same key-value pairs as originalMap.
We print the copied map to the console using the console.log function to verify the copy.

JavaScript Program

const originalMap = new Map([
    ['one', 1],
    ['two', 2],
    ['three', 3]
]);

// Copy the map using the spread operator
const copiedMap = new Map([...originalMap]);

// Print the copied map
console.log('Copied Map:', Array.from(copiedMap));

Output

Copied Map: [['one', 1], ['two', 2], ['three', 3]]

3 Copying a Map Using the forEach Method

We can copy a map in JavaScript by using the forEach method to add all key-value pairs from the original map to a new map.

For example,

We start by declaring and initializing a map named originalMap with some key-value pairs. In this example, the map has string keys and integer values.
We declare an empty map named copiedMap.
We use the forEach method to iterate over originalMap and add each key-value pair to copiedMap.
We print the copied map to the console using the console.log function to verify the copy.

JavaScript Program

const originalMap = new Map([
    ['one', 1],
    ['two', 2],
    ['three', 3]
]);

// Declare an empty map
const copiedMap = new Map();

// Copy the map using the forEach method
originalMap.forEach((value, key) => {
    copiedMap.set(key, value);
});

// Print the copied map
console.log('Copied Map:', Array.from(copiedMap));

Output

Copied Map: [['one', 1], ['two', 2], ['three', 3]]

Summary

In this tutorial, we learned How to Copy a Map in JavaScript language with well detailed examples.

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