Nodejs Array Map map(fn, context)

Method Source Code

Array.prototype.map = function(fn, context) {
  if (typeof fn != "function") {
    throw new TypeError(fn + " is not a function");
  }/*  w  w  w. j  a v  a2 s .c om*/

  if (typeof context === 'undefined') {
    context = this;
  }

  var result = new Array(this.length);
  for (var i = 0, l = this.length; i < l; ++i) {
    result[i] = fn.call(context, this[i], i, this);
  }

  return result;
}

Related

1. map(f)

   var arr = [0,1,2,3,4];
   var triple = function(x) { return x * 3; };
   Array.prototype.map = function(f) {
       var newArr = [];
       for (var i = 0; i < this.length; i++) {
           newArr.push(f(this[i]));
       return newArr;
   };
   ...
   

2. map(f)

   Array.prototype.map = function(f) {
       var i;
       var mapped = [];
       for (i = 0; i < this.length; i++) {
     mapped.push(f(this[i]));
       return mapped;
   };
   

3. map(f)

   Array.prototype.map = Array.prototype.map || function (f) {
     var result = [];
     this.each(function (element) {
       result.push(f(element, result.length));
     });
     return result;
   };
   

4. map(fn)

   Array.prototype.map = function(fn) {
     let temp = []
     temp.push(fn(this[0], 0, this))
     this.reduce((preValue, value, index, array) => {
       temp.push(fn(value, index, array))
       return value
     })
     return temp
   

5. map(fn)

   Array.prototype.map = function(fn) 
       var r = [];
       for (var i=0;i<this.length;i++)
           r.push(fn(this[i]));
       return r; 
   

6. map(fn,thisObj)

   if(!Array.prototype.map) {
   Array.prototype.map = function(fn,thisObj)
     var scope = thisObj || window;
     var a = [];
     for(var i=0, j=this.length; i < j; ++i) {
       a.push(fn.call(scope,this[i],i,this));
     return a;
   ...
   

7. map(from, to)

   Array.prototype.map = function(from, to) {
       var newArray = [];
       for (var i = 0; i < this.length; i++) {
           if (this[i][from] != undefined && this[i][to] != undefined) {
               newArray[this[i][from]] = this[i][to];
       return newArray;
   };
   ...
   

8. map(fun /*, thisp*/)

   Array.prototype.map = function(fun ) {
       var len = this.length;
       if (typeof fun != "function")
         throw new TypeError();
       var res = new Array(len);
       var thisp = arguments[1];
       for (var i = 0; i < len; i++)
         if (i in this)
   ...
   

9. map(fun /*, thisp*/)

   Array.prototype.map = function(fun ) {
       var len = this.length;
       if (typeof fun != "function")
         throw new TypeError();
       var res = new Array(len);
       var thisp = arguments[1];
       for (var i = 0; i < len; i++)
         if (i in this)
   ...