Nodejs Array Duplicate duplicate()

Method Source Code

//implement duplicate([1, 2, 3, 4, 5]) // [1,2,3,4,5,1,2,3,4,5]


function duplicate(arr) {
    var len = arr.length;
    for (var i = 0; i < len; i++) {
        console.log(arr[i]);//w  w w  .  j  ava  2s .co  m
        arr[len + i] = arr[i];
    }
    return arr;
}

// or [1,2,3].duplicate();

Array.prototype.duplicate = function () {
    var len = this.length;
    for (var i = 0; i < len; i++) {
        this[len + i] = this[i];
    }
    return 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;
   

5. duplicate()

   var arr1 = [3, 'a', 'a', 'a', 2, 3, 'a', 3, 'a', 2, 4, 9, 3];
   Array.prototype.duplicate = function () {
       return this.concat(this);
   console.log([4, 5, 6, 7, 7].duplicate());
   

6. duplicator()

   Array.prototype.duplicator = function() {
     var len = this.length;
     for (var i = 0; i < len; i++) {
       this.push(this[i]);
     return this;
   };
   console.log([1, 2, 3, 4, 5].duplicator());
   

7. dups()

   Array.prototype.dups = function () {
     const uniqArr = [];
     for (var i = 0; i < this.length; i++) {
       if (!uniqArr.includes(this[i])){
         uniqArr.push(this[i]);
     return uniqArr;
   };
   ...
   

8. dups()

   Array.prototype.dups = function() {
     var result = [];
     for(var i = 0; i < this.length; i++){
       if (result.indexOf(this[i]) === -1) {
         result.push(this[i]);
     return result;