• if you call obj.f(), the keyword this will be bound to obj
  
• if you call new f(), the keyword this will be bound to a new object.
  
• if you call f(), the keyword this will be bound to ~~the global namespace~~
  

• if you declare a function inside another function and use the outer function as a method, then within the inner function this still refers to the global namespace.
  
• if you write a function f() meant to be used as a constructor, using lots of this.prop = val kind of statements, and then accidentally call it without the new keyword, js will silently clobber the global namespace for you.
  

coffeetable fucked around with this message at 07:42 on Mar 20, 2014

Deus Rex fucked around with this message at 11:32 on Mar 20, 2014

hackbunny fucked around with this message at 09:51 on Mar 21, 2014

// arguments.callee
var fact0 = function (x) {
    if (x === 0)
        return 1;
    else
        return x * arguments.callee(x - 1);
};

alert(fact0(5)); // how else? just as god intended

// combinator
function F(f) {
    return function(x) {
        return f(f, x);
    };
}

var fact1 = function(f, x) {
    if (x === 0)
        return 1;
    else
        return x * f(f, x - 1);
};

alert(F(fact1)(5)); // a little like triple-indirected pointers in C

// Y-combinator
var fact2 = function(f) {
    return function(x) {
        if (x === 0)
            return 1;
        else
            return x * f(f)(x - 1);
    };
};

alert(fact2(fact2)(5)); // are you loving with me

var fact3 = F(fact1);
var fact4 = fact2(fact2);

hackbunny fucked around with this message at 11:05 on Mar 21, 2014