Nodejs Array Reduce reduce.call(str, (trav, char)>

Method Source Code

'use strict';//from w  w w  .  j av a2  s  . c  o  m

class PrefixTree {
    constructor() {
        this.root = {};
    }

    insert(str) {
        Array.prototype.reduce.call(str, (trav, char) => {
            if (!trav[char]) {
                trav[char] = {};
            } 

            return trav[char];
        }, this.root);
    }


}

let tree = new PrefixTree();
tree.insert('hello');
tree.insert('health');
console.log(tree);

function reduce(arr, fn, initialValue) {
    for (var i = 0;i < arr.length;i++) {

    }

}

Array.prototype.tonysReduce =  (fn, initialValue) => {
    console.log('this: ', this);
    for (let i = 0;i < this.length;i++) {
        console.log(initialValue);
        initialValue = fn(initialValue, this[i], i, this)
    }

    return initialValue;
};

let arr = [1,2,3,4];

let val = arr.tonysReduce((initialValue, num) => {
    return initialValue + num;
}, 0);

console.log(val);

Related

1. reduce(reducingFunction, initialValue)

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

2. reduce(t, fn)

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

3. 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){
   ...
   

4. 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){
   ...
   

5. 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){
   ...
   

6. reduceRight(aggregate, initial)

   Array.prototype.reduceRight = function(aggregate, initial) {
     const len = this.length;
     let startIndex = len - 1;
     if(typeof initial === 'undefined') {
       initial = this[0];
       startIndex = len - 2;
     for(let i = startIndex; i >= 0; i -= 1) {
       initial = aggregate(initial, this[i], i, this);
   ...
   

7. reduceRight(fun /*, initial*/)

   Array.prototype.reduceRight = 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 = len - 1;
   ...
   

8. reduceRight2(pasteback, initial)

   Array.prototype.reduceRight2 = function(pasteback, initial){
     for(var i = this.length
         , value = arguments.length>1 ? initial : this[--i]
     ; i--;){
       value = pasteback(value, this[i], i, this);
     return value;
   };
   

9. _reduce(f)

   Array.prototype._reduce = function(f){
       let acc = this[0];
       for(let i = 1; i < this.length; i++){
           acc = f(acc,this[i])
       return acc;