The Javascript array flatMap() is an inbuilt method in JavaScript that is used to flatten the input array element into a new array. This method first of all maps every element with the help of a mapping function, then flattens the input array element into a new array.
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, we will see the basic use of the array.flatMap() method for flattening an array.
javascript
// Taking input as an array A having some elements.let A = [1, 2, 3, 4, 5];// Mapping with map method.b = A.map(x => [x * 3]);console.log(b);// Mapping and flatting with flatMap() method.c = A.flatMap(x => [x * 3]);console.log(c);// Mapping and flatting with flatMap() method.d = A.flatMap(x => [[x * 3]]);console.log(d); |
[ [ 3 ], [ 6 ], [ 9 ], [ 12 ], [ 15 ] ] [ 3, 6, 9, 12, 15 ] [ [ 3 ], [ 6 ], [ 9 ], [ 12 ], [ 15 ] ]
Example 2: This flatting can also be done with the help of reducing and concat.
javascript
// Taking input as an array A having some elements.let A = [1, 2, 3, 4, 5];console.log(A.flatMap(x => [x * 3]))// is equivalent tob = A.reduce((acc, x) => acc.concat([x * 3]), []);console.log(b); |
[ 3, 6, 9, 12, 15 ] [ 3, 6, 9, 12, 15 ]
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.
