How to count duplicate value in an array in javascript

count_duplicate.js

// #1 Solution
var arr = ['a','b','c','d','d','e','a','b','c','f','g','h','h','h','e','a'];
var map = arr.reduce(function(prev, cur) {
  prev[cur] = (prev[cur] || 0) + 1;
  return prev;
}, {});

// map is an associative array mapping the elements to their frequency:
document.write(JSON.stringify(map));
// prints {"a": 3, "b": 2, "c": 2, "d": 2, "e": 2, "f": 1, "g": 1, "h": 3}

// #2 Solution
function count() {
    var arr = ["a", "b", "c", "d", "e", "a", "b", "c", "f", "g", "h", "h", "h", "e", "a"];
    arr.sort();
    var current = null;
    var cnt = 0;
    for (var i = 0; i < arr.length; i++) {
        if (arr[i] != current) {
            if (cnt > 0) {
                document.write(current + ' comes --> ' + cnt + ' times<br>');
            }
            current = arr[i];
            cnt = 1;
        } else {
            cnt++;
        }
    }
    if (cnt > 0) {
        document.write(current + ' comes --> ' + cnt + ' times');
    }
}

count();