Array.prototype.fill()
Fills all or part of an array with a static value in place.
Syntax
arr.fill(value, start, end)Parameters
| Name | Type | Required | Description |
|---|---|---|---|
value | any | Yes | The value to fill the array with. |
start | number | No | Index to start filling. Negative counts from the end. Defaults to 0. |
end | number | No | Index before which to stop (exclusive). Negative counts from the end. Defaults to array length. |
Returns
Array — The modified array (same reference).
Examples
console.log([1, 2, 3, 4].fill(0, 1, 3));
Output
[ 1, 0, 0, 4 ]
console.log(new Array(3).fill('x'));
Output
[ 'x', 'x', 'x' ]
Notes
Mutates the array in place. When filling with an object, every slot references
the same object. Commonly used with `Array(n).fill()` to initialize arrays.
Browser & runtime support
| Environment | Since version |
|---|---|
| chrome | 45 |
| firefox | 31 |
| safari | 7.1 |
| edge | 12 |
| node | 4.0 |