SICP in javascript

factorial.js

var factorial = (function () {
	"use strict";
	
	function fact (product, counter, x) {
		return counter > x ? product : fact(counter * product, counter + 1, x);
	}
	
	return function (x) {
		return fact(1, 1, x);
	};
})();

sqrt.js

var sqrt = (function () {
	"use strict";
	
	function sqrt (n, x, p) {
		return Math.abs(x*x - n) < p ? x : sqrt(n, (n/x + x) / 2, p);
	}
	
	return function (n) {
		return sqrt(n, 1, 0.001);
	};
})();