title: countOccurrences tags: array,intermediate

Counts the occurrences of a value in an array.

Use Array.prototype.reduce() to increment a counter each time you encounter the specific value inside the array.

const countOccurrences = <T = any>(arr: T[], val: T) =>
  arr.reduce((a, v) => (v === val ? a + 1 : a), 0);

countOccurrences([1, 1, 2, 1, 2, 3], 1); // 3