Nodejs Array Reduce reduce()

Method Source Code

var testArray1 = [1, 3, 5, 4, 2],
//    sumArray;//w  w  w. j av a2s  .c om
      sumArray = [];

Array.prototype.reduce = function() {
   var sum = 0;
    for (i=0;i<this.length; ++i) {
    sum += this[i];
    }
//    return sumArray = [sum];
      return sumArray.push(sum);
};
testArray1.reduce();
console.log(sumArray);

Related

1. reduce()

   Array.prototype.reduce = function() {
     return this.length > 1 ? this : this[0];
   };
   

2. reduce(aggregate, initial)

   Array.prototype.reduce = function(aggregate, initial) {
     const len = this.length;
     let startIndex = 0;
     if(typeof initial === 'undefined') {
       initial = this[0];
       startIndex = 1;
     for(let i = startIndex; i < len; i += 1) {
       initial = aggregate(initial, this[i], i, this);
   ...
   

3. reduce(callback, initial)

   Array.prototype.reduce = function(callback, initial){
     initial = initial || 0;
     for (var i=0; i< this.length; i++) {
       initial = callback(initial, this[i], i, this);
     return  initial;
   wat = [1,2, 3, 4]
   console.log(wat);
   ...
   

4. reduce(callback, initialValue)

   Array.prototype.reduce = function(callback, initialValue) {
     var last, returned;
     this.forEach(function(item, index, array) {
       if (index == 0 && initialValue) {
         returned = initialValue;
       } else if (index == 1 && !initialValue) {
         returned = item;
       } else {
         last = returned, returned = null;
   ...
   

5. reduce(callback, memo)

   Array.prototype.reduce = function (callback, memo) {
       var obj = this;
       var value, accumulated_value = 0;
       for (var i = 0; i < obj.length; i++) {
           value = obj[i];
           accumulated_value = callback.call(null, accumulated_value, value);
       return accumulated_value;
   };
   ...