Nodejs Array Item Occurrence numberOfOccurrences( arg )

Method Source Code

// 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( arg ) {
  var num = 0;/*from  w  w  w.j  av a2  s . c  om*/
  this.forEach( function( e ){
    if ( arg === e ) { num++; }
  });
  return num;
};

var arr = [0,1,2,2,3,"a"];

console.log( arr.numberOfOccurrences("a") );

Related

1. numberOfOccurrences(arr)

   Array.prototype.numberOfOccurrences = function (arr) {
       var elem = 0;
       for (var i = 0; i < this.length; i++) {
           if (this[i] === arr) {
               elem++;
       return elem;
   };
   ...
   

2. numberOfOccurrences(chr)

   Array.prototype.numberOfOccurrences = function(chr) {
     return this.filter(function(x){ return x == chr; }).length;
   

3. numberOfOccurrences(desVal)

   Array.prototype.numberOfOccurrences = function(desVal) {
     var counter = 0;
     this.forEach(function(value){
       if(value === desVal){
         counter++;
     });
     return counter;
   };
   ...
   

4. numberOfOccurrences(el)

   Array.prototype.numberOfOccurrences = function (el) {
     var count = 0;
     this.forEach(function (item) {
       if (item === el) count++;
     });
     return count;