18 lines
541 B
Markdown
18 lines
541 B
Markdown
### indexOfAll
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Returns an array of indexes at which the `val` occurs in `arr`. If it occurs only once return the `index` and if it never occurs returns `-1`
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``` js
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const indexOfAll = (arr, val) => {
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let indexes = [], i;
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arr.forEach((el,i) => {if(el === val) indexes.push(i)})
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return indexes.length === 0 ? [-1] : indexes
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}
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```
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``` js
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indexOfAll([1,2,3],1); // [0]
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indexOfAll([1,2,3,1,2,3],1); // [0,3]
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indexOfAll([1,2,3],4); // [-1]
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indexOfAll([[1,2,3]],[1,2,3]); // [-1] (Array.prototype.indexOf()) has the same behaviour
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```
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