Question

When entered into a JavaScript console, a jQuery object appears as an array. However, it’s still an instance of the jQuery object.

var j = jQuery();
=> []
console.log(j);
=> []
console.log('test with string concat: ' + j);
=> test with string concat: [object Object]
j instanceof Array
=> false
j instanceof jQuery
=> true

How could one duplicate this with their own object?

——— EDIT ———

Thanks to ZER0 for figuring it out. Here’s some example code to create an object that works just like jQuery in the console:

var Foo = function() {
  this.splice = Array.prototype.splice;
  Array.prototype.push.apply(this, arguments);

  return this;
}

var f = new Foo();
=> []
console.log(f);
=> []
console.log('test with string concat: ' + f);
=> test with string concat: [object Object]
f instanceof Array
=> false
f instanceof Foo
=> true

Very cool.

Answer 1

I believe they have something like that:

// Adding items to an object like an Array:
var myObject = {splice : Array.prototype.splice};

Array.prototype.push.call(myObject, 1, 10, "foo");

// Getting items from an object like an Array:

alert(Array.prototype.slice.call(myObject, 0));

console.log(myObject);

alert(myObject);