Y Combinator

//first self reference
var fact = function(self){
	return function(n){
		if(n == 0) return 1;
		else return n * self(self)(n-1);
	}
}
console.log(fact(fact)(10));

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

console.log(fact1(fact1)(10));

//take out f of fact1
var f = function(self){
	return function(x){
		if (x == 0) return 1;
		else return x * self(x - 1);
	}
}
var fact2 = function(self){
	return function(n){
		return f(self(self))(n);
	}
}

console.log(fact2(fact2)(10));

// abstract Y

var Y = function(f){
		var g = function(self){
			return function(n){
				return f(self(self))(n);
			}
		}
		return g(g);
}
console.log(Y(f)(10));