fact.js

var fact = (function (fact) {
	return (function (f) {
		return f(function (f) {
			return fact(function (n) {
				return f(f)(n)
			})
		})
	})(function (f) { 
		return f(f)
	})
})(function (f) {
	return function (n) {
		return n == 0 ? 1 : n * f(n - 1)
	}
})

console.log(fact(5))