Most frequent element in array
JavaScript, Array · Sep 15, 2020

Returns the most frequent element in an array.
- Use
Array.prototype.reduce()
to map unique values to an object's keys, adding to existing keys every time the same value is encountered. - Use
Object.entries()
on the result in combination withArray.prototype.reduce()
to get the most frequent value in the array.
const mostFrequent = arr => Object.entries( arr.reduce((a, v) => { a[v] = a[v] ? a[v] + 1 : 1; return a; }, {}) ).reduce((a, v) => (v[1] >= a[1] ? v : a), [null, 0])[0]; mostFrequent(['a', 'b', 'a', 'c', 'a', 'a', 'b']); // 'a'