30-seconds-of-code/snippets/countOccurrences.md

title, tags, cover, firstSeen, lastUpdated

title	tags	cover	firstSeen	lastUpdated
Count occurrences	array	blog_images/dark-leaves-4.jpg	2017-12-17T17:55:51+02:00	2020-10-18T23:04:45+03:00

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