Nodejs Array Sum sum(func)

Method Source Code

Array.prototype.sum = function (func) {
    var length = this.length,
        sum = 0;//from  w  w w  . j ava2s. c  om

    for (var i = 0; i < length; i++) {
        sum += func(this[i]);
    }

    return sum;
}


function isUndefinedNullOrEmpty(item) {
    return item === undefined || item === null || item === '';
}

Related

1. sum()

   Array.prototype.sum = function() {
     return this.isEmpty() ? 0 : this.reduce( (a, b) => { return a + b} );
   };
   

2. sum()

   Array.prototype.sum = function() {
     for ( var a = 0, c = this.length, b = 0; a < c; b += this[a++]) {
     return b
   };
   

3. sum(array)

   Array.prototype.sum = function(array) { 
       return this.reduce(function(a,b) { 
           return a + b 
       }) 
   

4. 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;
   };
   

5. sum(fun)

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

6. 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;
   };
   

7. 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;
   };
   

8. sum(selector)

   Array.prototype.sum = function(selector) {
       if (typeof selector !== 'function') {
           selector = function(item) {
               return item;
       var sum = 0;
       for (var i = 0; i < this.length; i++) {
           sum += selector(this[i]);
   ...
   

9. sum(selectorfun)

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