jQuery object is an array like object

jQuery object is not an Array object, but it looks like an array. The following code how this is implemented?

var o = {"0":1, "1": 2, length:2};
var a = [].slice.call(o, 0);
alert(a); // 1, 2


//or you can do this
var o = {}
o[0] = 1;
o.length = 1;
o[1] = 2;
o.length = 2;
var a = [].slice.call(o, 0);
alert(a); // 1, 2

//or you can do this
var o = {};
[].push.call(o, 1);
[].push.call(o, 2);
var a = [].slice.call(o, 0);
alert(a); // 1, 2