17 lines
407 B
Markdown
17 lines
407 B
Markdown
### indexOfAll
|
|
|
|
Returns all indices of `val` in an array.
|
|
If `val` never occurs, returns `[]`.
|
|
|
|
Use `Array.reduce()` to loop over elements and store indices for matching elements.
|
|
Return the array of indices.
|
|
|
|
```js
|
|
const indexOfAll = (arr, val) => arr.reduce((acc, el, i) => (el === val ? [...acc, i] : acc), []);
|
|
```
|
|
|
|
```js
|
|
indexOfAll([1, 2, 3, 1, 2, 3], 1); // [0,3]
|
|
indexOfAll([1, 2, 3], 4); // []
|
|
```
|