JavaScript Array flatMap() Method
Last Updated :
05 Dec, 2023
JavaScript Array flatMap()
method is used to both flatten and map elements of an array. It works by applying a provided function to each element of the array and then flattening the result into a new array.
This method is used in JavaScript to both map over the elements of an array and flatten the result into a new array. This is particularly handy when you want to perform a mapping operation that might return arrays for each element, and you want the final result to be a single flattened array.
Example:
const words = ["Hello", "world", "how", "are", "you"];
const result = words.flatMap(word => word.split(''));
console.log(result); // Output: ["H", "e", "l", "l", "o", "w", "o", "r", "l", "d", "h", "o", "w", "a", "r", "e", "y", "o", "u"]
Syntax:
let A = array.flatMap(function callback(current_value, index, Array)) {
// It returns the new array's elements.
}
Parameters:
- current_value: It is the input array element.
- index:
- It is optional.
- It is the index of the input element.
- Array:
- It is optional.
- It is used when an array map is called.
Return Values: It returns a new array whose elements are the return value of the callback function.
Example 1: In this example, the flatMap()
method is utilized to perform a dual operation on an array of numbers. Each number is both doubled and squared using a callback function, resulting in a new array. The flatMap()
function ensures that the individual arrays produced for each number are flattened into a single array, producing the final array with doubled and squared values.
javascript
const numbers = [1, 2, 3, 4];
const doubledAndSquared = numbers.flatMap(num => [num * 2, num ** 2]);
console.log(doubledAndSquared);
|
Output
[
2, 1, 4, 4,
6, 9, 8, 16
]
Example 2: In this example, the flatMap()
method is employed to process an array of sentences. The callback function, sentence => sentence.split(' ')
, is applied to each sentence, splitting it into an array of words. The flatMap()
method then flattens these arrays into a single-dimensional array of words.
javascript
const sentences = [ "Hello world" , "How are you?" , "JavaScript is fun" ];
const words = sentences.flatMap(sentence => sentence.split( ' ' ));
console.log(words);
|
Output
[ 'Hello', 'world', 'How', 'are', 'you?', 'JavaScript', 'is', 'fun' ]
We have a complete list of Javascript Array methods, to check those please go through this Javascript Array Complete reference article.
Supported Browser:
- Google Chrome 69 and above
- Edge 79 and above
- Firefox 62 and above
- Opera 56 and above
- Safari 12 and above
Note: This method is available in Firefox Nighty only.
We have a Cheat Sheet on Javascript where we covered all the important topics of Javascript to check those please go through Javascript Cheat Sheet-A Basic guide to JavaScript.
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