Nodejs Array Duplicate duplicate()

Method Source Code

Array.prototype.duplicate = function() {
    return (this + ',' + this);
};

Related

1. duplicate()

   Array.prototype.duplicate = function(){
     var newArr = this.slice();
     for(var i = 0; i < this.length; i ++){
       newArr.push(this[i]);
     return newArr;
   };
   console.log([1, 2, 3, 4].duplicate());
   

2. duplicate()

   Array.prototype.duplicate = function(){
     return this.concat(this);
   duplicate([1,2,3,4,5])
   

3. duplicate()

   function duplicateArray(arr) {
     return arr.concat(arr);
   Array.prototype.duplicate = function() {
     return this.concat(this);
   console.log([1,2,3,4,5].duplicate());
   console.log(duplicateArray([1,2,3,4,5]));
   

4. duplicate()

   Array.prototype.duplicate = function(){
     var arrayVal = this;
     this.forEach(function(val){
       arrayVal.push(val);
     })
     return arrayVal;