Ways to extend Array object in javascript

Question

i try to extend Array object in javascript with some user friendly methods like Array.Add() instead Array.push() etc...

i implement 3 ways to do this. unfortunetly t

Answer 1

var SubArray = function() {                                           
    var arrInst = new Array(...arguments); // spread arguments object
    /* Object.getPrototypeOf(arrInst) === Array.prototype */
    Object.setPrototypeOf(arrInst, SubArray.prototype);     //redirectionA
    return arrInst; // now instanceof SubArray
};

SubArray.prototype = {
    // SubArray.prototype.constructor = SubArray;
    constructor: SubArray,

    // methods avilable for all instances of SubArray
    add: function(element){return this.push(element);},
    ...
};

Object.setPrototypeOf(SubArray.prototype, Array.prototype); //redirectionB

var subArr = new SubArray(1, 2);
subArr.add(3); subArr[2]; // 3

The answer is a compact workaround which works as intended in all supporting browsers.

Answer 2

In your third example you're just creating a new property named prototype for the object Array3. When you do new Array3 which should be new Array3(), you're instantiating that object into variable list3. Therefore, the Add method won't work because this, which is the object in question, doesn't have a valid method push. Hope you understand.

Edit: Check out Understanding JavaScript Context to learn more about this.