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