8ee50178f3
Correct: `Array.from()` (it’s a static method) Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method) This patch uses the common `#` syntax to denote `.prototype.`.
14 lines
342 B
Markdown
14 lines
342 B
Markdown
### countOccurrences
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Counts the occurrences of a value in an array.
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Use `Array.prototype.reduce()` to increment a counter each time you encounter the specific value inside the array.
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```js
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const countOccurrences = (arr, val) => arr.reduce((a, v) => (v === val ? a + 1 : a), 0);
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```
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```js
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countOccurrences([1, 1, 2, 1, 2, 3], 1); // 3
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```
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