Count Occurrences

Count occurrences of array elements

by svaqqosov

JavaScript

var arr = [2, 2, 2, 2, 2, 4, 5, 5, 5, 9];

const countOccurrences = (arr) => {
    const map = {};
    for ( var i = 0; i < arr.length; i++ ) {
        map[arr[i]] = ~~map[arr[i]] + 1;
    }
    return map;
}

var result = countOccurrences(arr);
document.write(JSON.stringify(result));