Javascript: how to detect array calls?

Question

I have question about native javascript calling.

i have a class:

x = function(arr) { this.arr = arr; return this; }
x.prototype.toArray = function() {
       return this.arr;
};
x.prototype.test = function() { alert('but i m object too!'); };

when i calling:

var test = new x(['a','b','c']);

alert(test[0]);

alert(test.test());

need to get result 'a' and 'but i m object too!' dialogs.

I want to use this feature as syntax sugar like uses jquery in core when returning DOM Elements after using selector as array. How to implement that?

UPDATE:

Thank for answer, but i need proofs in jquery code blob on github.

Answer 1

An array is nothing else than an object which treats numeric properties in a special way. You would have to copy every element of the array to the instance, using the index of the element as property name. You should also set the length attribute, to make it a true "array-like" object.

var X = function(arr) {
    for (var i = 0, l = arr.length; i < l; i++) {
        this[i] = arr[i];
    }
    this.length = arr.length;
};

var x = new X(['a', 'b', 'c']);
alert(x[0]);