Nodejs Array Sum sum(selector)

Method Source Code

Array.prototype.sum = function(selector) {
    if (typeof selector !== 'function') {
        selector = function(item) {
            return item;
        }/*from   w ww.j  a v a2  s  .co  m*/
    }
    var sum = 0;
    for (var i = 0; i < this.length; i++) {
        sum += selector(this[i]);
    }
    return sum;
};

String.prototype.contains = function(it) {
    return this.indexOf(it) != -1; 
};

Related

1. sum(begin, end)

   Array.prototype.sum = function(begin, end) {
     var total = 0;
     for (var i = begin >> 0 || 0, len = end + 1 >> 0 || this.length >> 0; i < len; i++) {
       total += +this[i] || 0;
     return total;
   };
   

2. sum(fun)

   Array.prototype.sum = function (fun) {
       var result = 0;
       this.forEach(x => result += fun ? fun(x) : x);
       return result;
   };
   

3. sum(func)

   Array.prototype.sum = function (func) {
       var length = this.length,
           sum = 0;
       for (var i = 0; i < length; i++) {
           sum += func(this[i]);
       return sum;
   function isUndefinedNullOrEmpty(item) {
   ...
   

4. sum(prop)

   Array.prototype.sum = function (prop) {
       var total = 0;
       for ( var i = 0, _len = this.length; i < _len; i++ ) {
           total += this[i][prop]
       return total;
   };
   

5. sum(s)

   Array.prototype.sum = function (s) {
     s = s || Selector;
     var l = this.length;
     var sum = 0;
     while (l-- > 0) sum += s(this[l]);
     return sum;
   };
   

6. sum(selectorfun)

   Array.prototype.sum = function(selectorfun)
     if (selectorfun)
       return this.map(selectorfun).sum();
     else
       var ret = 0;
   ...
   

7. sum(xAndY)

   Array.prototype.sum = function(xAndY){
     var count = 0;
     for(var i = 0; i < this.length; i++)
       count += xAndY(this[i])
     return count;
   

8. sumArrayItems()

   Array.prototype.sumArrayItems = function() {
     var countIndex = this.length - 1;
     var sum =0;
     while ( countIndex >= 0) {
       sum = sum + this[ countIndex ];
       countIndex--;
     return sum;
   var findMissing = function( arr1 , arr2 ) {
     return Math.abs( arr1 - arr2);
   findMissing([1,2].sumArrayItems() , [1,2,5].sumArrayItems());
   

9. sumItems()

   Array.prototype.sumItems = function(){
     var sum = 0;
     for(var i=0; i<this.length; i++){
       sum=sum+this[i];
     return(sum);
   var arr = new Array;
   arr = [5,10];
   ...