2010 11 10 false advertising

What do you think this constructor returns for new Dude('Bob')? Doug or Bob?

    function Dude(name){
        this.name = name;
        return {name: 'Doug'};
    }

Answer:

    var bob = new Dude('Bob');
    // { name: 'Doug' }
    bob instanceof Dude
    // false

Huh!? So you can just slip in anything? What about arrays?

    function Dude(name){
        this.name = name;
        return [1, 2, 3];
    }
    new Dude('Bob');
    // [1, 2, 3]

That can't be! What about...

    function Dude(name){
        this.name = name;
        return 3;
    }
    new Dude('Bob');
    // { name: 'Bob' }

Wah? No way! So, if you try to return a primitive type from a constructor(number, string, date), it will ignore the return value and return the originally initialized object, but otherwise, the returned value overrides.

--- @airportyh