20 lines
597 B
Markdown
20 lines
597 B
Markdown
### indexesOf
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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 indexesOf = (arr, val) => {
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let indexes = [], i;
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for(i = 0; i < arr.length; i++)
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if (arr[i] === val)
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indexes.push(i);
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return indexes.length === 0 ? -1 : indexes.length === 1 indexes.pop() : indexes
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}
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```
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``` js
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indexesOf([1,2,3],1); // 0
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indexesOf([1,2,3,1,2,3],1); // [0,3]
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indexesOf([1,2,3],4); // -1
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indexesOf([[1,2,3]],[1,2,3]); // -1 (Array.prototype.indexOf()) has the same behaviour
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```
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