JavaScript Map forEach() Method (original) (raw)

Last Updated : 12 Jul, 2024

JavaScript Map.forEach method is used to loop over the map with the given function and executes the given function over each key-value pair.

**Syntax:

myMap.forEach(callback, value, key, thisArg)

**Parameters:

This method accepts four parameters as mentioned above and described below:

• **callback: This is the function that executes on each function call.
• **value: This is the value for each iteration.
• **key: This is the key to reach iteration.
• **thisArg: This is the value to use as this when executing callback.

**Return Value:

• It returns the undefined value.

**Example 1: In this example, The forEach method is used to log each key-value pair to the console.

JavaScript `

// Creating a map using Map object let mp = new Map()

// Adding values to the map mp.set("a", 1); mp.set("b", 2); mp.set("c", 3);

// Logging map object to console mp.forEach((values, keys) => { console.log(values, keys) })

`

**Output:

1a
2b
3c

**Example 2: In this example, the forEach method is employed to iterate through the map, printing each key-value pair to the console in the format “values: [value], keys: [key]”.

JavaScript `

// Creating a map using Map object let mp = new Map()

// Adding values to the map mp.set("a", 65); mp.set("b", 66); mp.set("c", 67); mp.set("d", 68); mp.set("e", 69); mp.set("f", 70);

// Logging map object console.log(mp); mp.forEach((values, keys) => { console.log("values: ", values + ", keys: ", keys) })

`

**Output:

[object Map]
values: 65, keys: a
values: 66, keys: b
values: 67, keys: c
values: 68, keys: d
values: 69, keys: e
values: 70, keys: f

**Example 3: This example shows the basic use of the JavaScript **Map.forEach() method.

JavaScript `

let mp = new Map();

// adding values to the map mp.set("a", 65); mp.set("b", 66); mp.set("c", 67); mp.set("d", 68); mp.set("e", 69); mp.set("f", 70);

// logging map object to console console.log(mp);

// logging concatenated keys and values mp.forEach((value, key) => { console.log(key+": " + value); });

`

Output

Map(6) { 'a' => 65, 'b' => 66, 'c' => 67, 'd' => 68, 'e' => 69, 'f' => 70 } a: 65 b: 66 c: 67 d: 68 e: 69 f: 70

We have a complete list of Javascript Map Methods, to check those please go through Javascript Map Complete Reference article.

**Browsers Supportes:

• Google Chrome
• Microsoft Edge
• Mozilla Firefox
• Safari
• Opera