In this Article we will go through how to count the occurrences of array elements only using single line of code in JavaScript.
This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.
Let's define this short function:
const countOccurrences = arr => arr.reduce((prev, curr) => (prev[curr] = ++prev[curr] || 1, prev), {});
countOccurrences([2, 1, 3, 3, 2, 3]); // { '1': 1, '2': 2, '3': 3 }
countOccurrences(['a', 'b', 'a', 'c', 'a', 'b']); // { 'a': 3, 'b': 2, 'c': 1 }