Count occurrences
JavaScript, Array · Oct 18, 2020

Counts the occurrences of a value in an array.
- Use
Array.prototype.reduce()
to increment a counter each time the specific value is encountered inside the array.
const countOccurrences = (arr, val) =>
arr.reduce((a, v) => (v === val ? a + 1 : a), 0);
countOccurrences([1, 1, 2, 1, 2, 3], 1); // 3