You can sort the elements and loop through them:

array_elements = [2, 1, 2, 2, 3, 4, 3, 3, 3, 5];



array_elements.sort();



var current = null;

var cnt = 0;

for (var i = 0; i < array_elements.length; i++) {

    if (array_elements[i] != current) {

        if (cnt > 0) {

            document.write(current + ' comes --> ' + cnt + ' times<br>');

        }

        current = array_elements[i];

        cnt = 1;

    } else {

        cnt++;

    }

}

if (cnt > 0) {

    document.write(current + ' comes --> ' + cnt + ' times');

}

Demo: http://jsfiddle.net/Guffa/aQsuP/