14 lines
467 B
Markdown
14 lines
467 B
Markdown
### Count occurrences of a value in array
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Use `filter()` to create an array containing only the items with the specified value, count them using `length`.
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```js
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var countOccurrences = (arr, value) => arr.filter(v => v === value).length;
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```
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Use reduce() to increment a counter each time you encounter the specific value; does not create new array like filter().
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```js
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var countOccurrences = (arr, value) => arr.reduce((a, v) => v===value ? a + 1 : a + 0, 0);
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```
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