Javascript Array numberOfOccurrences(value)

/*/*from  ww w.java2s .c o m*/

The numberOfOccurrences function must return the number of occurrences of an element in an array.

var arr = [0,1,2,2,3];
arr.numberOfOccurrences(0) === 1;
arr.numberOfOccurrences(4) === 0;
arr.numberOfOccurrences(2) === 2;
arr.numberOfOccurrences("a") === 0;
*/

Array.prototype.numberOfOccurrences = function(value) {
  var count = 0;
  this.forEach(function(elem, index){
    if(elem === value){
      count++;
    }
  });
  return count;
};