Open In App

JavaScript Map forEach() Method

Improve
Improve
Improve
Like Article
Like
Save Article
Save
Share
Report issue
Report

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.

Returns: 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 Supported: 

  • Google Chrome 38 and above
  • Microsoft Edge 12 and above
  • Mozilla Firefox 25 and above
  • Internet Explorer 11 and above
  • Safari 8 and above
  • Opera 25 and above


Last Updated : 04 Dec, 2023
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads