Nodejs Array Reduce reduce(process, initial)

Method Source Code

Array.prototype.reduce = function(process, initial) {
  var value = initial;
  for (var i = 0; i < this.length; i++) {
    if( ( i === 0 ) && ( value === undefined || value === null ))
    {/*from  ww w. j av a 2  s .  c om*/
        value = this[0];
        continue;
    }
    value = process( value, this[i] );
  }
  return value;
};

Related

1. reduce(fn, initialValue)

   Array.prototype.reduce = function (fn, initialValue) {
     let acc = initialValue
     for (var i = 0; i < this.length; i++) {
       acc = fn(acc, this[i], i)
     return acc
   Array.prototype.forEach = function (fn) {
     this.reduce((acc, curr, i) => {
   ...
   

2. reduce(fun /* , initial */)

   if (!Array.prototype.reduce) {
     Array.prototype.reduce = function(fun ) {
       var len = this.length >>> 0;
       if (typeof fun != "function")
         throw new TypeError();
       if (len == 0 && arguments.length == 1)
         throw new TypeError();
       var i = 0;
       if (arguments.length >= 2) {
   ...
   

3. reduce(fun /*, initial*/)

   Array.prototype.reduce = function(fun )
     var len = this.length;
     if (typeof fun != "function") {
       throw new TypeError();
     if (len == 0 && arguments.length == 1) {
       throw new TypeError();
     var i = 0;
     if (arguments.length >= 2) {
       var rv = arguments[1];
     } else {
       do {
         if (i in this) {
           rv = this[i++];
           break;
         if (++i >= len) {
           throw new TypeError();
       } while (true);
     for (; i < len; i++) {
       if (i in this) {
         rv = fun.call(null, rv, this[i], i, this);
     return rv;
   };
   

4. reduce(fun /*, initial*/)

   Array.prototype.reduce = Array.prototype.reduce || function(fun ) {
       var len = this.length >>> 0;
       if (typeof fun != "function") {
           throw new TypeError();
       if (len == 0 && arguments.length == 1) {
           throw new TypeError();
       var i = 0;
   ...
   

5. reduce(pasteback, initial)

   'use strict';
   Array.prototype.reduce = function(pasteback, initial){
     for(var i = 0
         , c =  this.length
         , value = arguments.length>1 ? initial : this[i++]
     ; i<c; i++){
       value = pasteback(value, this[i], i, this);
     return value;
   ...
   

6. reduce(process, initial)

   Array.prototype.reduce = function(process, initial) {
     if (initial === undefined) {
       var slice = this.slice(1);
       initial = this[0];
     var array = slice || this;
     array.forEach(function(value) {
       initial = process(initial, value);
     });
   ...
   

7. reduce(reducingFunction, initialValue)

   Array.prototype.reduce = function(reducingFunction, initialValue) {
     var result = initialValue;
     this.forEach(function(x) {
       reducingFunction(result, x)
     });
     return result;
   

8. reduce(t, fn)

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

9. reduce(testFunction,initialValue)

   Array.prototype.reduce = function(testFunction,initialValue){
     var accumulatedValue,counter;
     if(this.length == 0){
       return this;
     }else{
       if(arguments.length == 1){
         counter = 1;
         accumulatedValue = this[0];
       }else if(arguments.length >= 2){
   ...