JavaScript | array.flatMap()
The array.flatMap() is an inbuilt function in JavaScript which is used to flatten the input array element into a new array.
This method first of all map every element with the help of mapping function, then flattens the input array element into a new array.
Syntax:
var A = array.flatMap(function callback(current_value, index, Array))
{
// It returns the new array's elements.
}Parameters:
- current_value: It is the input array elements.
- index:
- It is optional.
- It is the index of the input element.
- Array:
- It is optional.
- It is used when array map is called.
Return Values: It returns a new array whose elements are the return value of the callback function.
JavaScript code to show the functionality of the above function:
Code #1:
javascript
<script>// Taking input as an array A having some elements.var A = [ 1, 2, 3, 4, 5 ];// Mapping with map function.b = A.map(x => [x * 3]);document.write(b);// Mapping and flatting with flatMap() function.c = arr1.flatMap(x => [x * 3]);document.write(c);// Mapping and flatting with flatMap() function.d = arr1.flatMap(x => [[ x * 3 ]]);document.write(d);</script> |
Output:
[[3], [6], [9], [12], [15]] [3, 6, 9, 12, 15] [[3], [6], [9], [12], [15]]
Code #2: This flatting can also be done with the help of reduce and concat.
javascript
<script>// Taking input as an array A having some elements.var A = [ 1, 2, 3, 4, 5 ];array.flatMap(x => [x * 3]);// is equivalent tob = A.reduce((acc, x) => acc.concat([ x * 3 ]), []);document.write(b);</script> |
Output:
[3, 6, 9, 12, 15]
Supported Browser:
- Google Chrome
- Microsoft Edge
- Firefox
- Opera
- Safari
Note: This function is available in Firefox Nightly only.
