Nodejs Array Reduce reduce(f, firstValue)

Method Source Code

Array.prototype.reduce = function(f, firstValue){
   var value = firstValue;
   for (var i =0; i<this.length; i++){
      value = f(this[i], value);//from  ww w  .j  a va 2  s  . c  om
   }
   return value;
};
[1,2,3].reduce(function(currentValue ,value){return value+=currentValue;}, 0);
[1,2,3].reduce(function(currentValue ,value){return value*=currentValue;}, 0);

Related

1. reduce(combiner, initialValue)

   Array.prototype.reduce = function (combiner, initialValue) {
     var counter,
       accumulatedValue;
     if (this.length === 0) {
       return this;
     else {
       if (arguments.length === 1) {
         counter = 1;
   ...
   

2. reduce(combiner, initialValue)

   Array.prototype.reduce = function(combiner, initialValue) {
     var counter,
       accValue;
     if (this.length === 0) {
       return this;
     else {
       if (arguments.length === 1) {
         counter = 1;
   ...
   

3. reduce(combiner, initialValue)

   Array.prototype.reduce = function(combiner, initialValue) {
     var counter,
       accumulatedValue;
     if (this.length === 0) {
       return this;
     else {
       if (arguments.length === 1) {
         counter = 1;
   ...
   

4. reduce(combiner, initialValue)

   Array.prototype.reduce = function (combiner, initialValue) {
     var counter,
       accumulatedValue;
     if (this.length === 0) {
       return this;
     if (arguments.length === 1) {
       counter = 1;
       accumulatedValue = this[0];
   ...
   

5. reduce(combiner, initialValue)

   Array.prototype.reduce = function(combiner, initialValue) {
     var counter,
       accumulatedValue;
     if (this.length === 1) {
       return this;
     } else {
         if (arguments.length === 1) {
           counter = 1;
           accumulatedValue = this[0];
   ...
   

6. reduce(f, inital)

   var arr = [0,1,2,3,4];
   var sum = function(x, y) { return x + y; };
   Array.prototype.reduce = function(f, inital) {
       var acc = initial;
       for (var i = 0; i < this.length; i++) {
           acc = f(acc, this[i]);
       return acc;
   };
   ...
   

7. reduce(f, initial)

   var arr = [0,1,2,3,4];
   var sum = function(total, newValue) { return total + newValue; };
   Array.prototype.reduce = function(f, initial) {
       var acc = initial;
       for (var i = 0; i < this.length; i++) {
           acc = f(acc, this[i]);
       return acc;
   };
   ...
   

8. reduce(f, value)

   Array.prototype.reduce = function (f, value) { 
       for (var i = 0; i < this.length; i++) { 
           value = f(this[i], value)
       return value
   

9. reduce(f, value)

   Array.prototype.reduce = function (f, value) {
     for (var i = 0, len = this.length; i < len; i++) {
       value = f(this[i], value);
     return value;
   };
   var superheroes = ['superman', 'iron man', 'spiderman', 'batman'];
   var totalLength = superheroes.reduce(function (elem, acc) {
     return elem.length + acc;
   ...