javascript array statistics count per value code example
Example 1: javascript Count the occurrences of a value in an array
const countOccurrences = (arr, val) => arr.reduce((a, v) => (v === val ? a + 1 : a), 0);
countOccurrences([2, 1, 3, 3, 2, 3], 2);
countOccurrences(['a', 'b', 'a', 'c', 'a', 'b'], 'a');
Example 2: javascript Count the frequency of a value in an array
const countOccurrences = arr => arr.reduce((prev, curr) => (prev[curr] = ++prev[curr] || 1, prev), {});
countOccurrences([2, 1, 3, 3, 2, 3]);
countOccurrences(['a', 'b', 'a', 'c', 'a', 'b']);