js master class

gistfile1.txt

Function.prototype.cached = function() {
	var cache = {},
		that = this;

	return function(arg) {
		if(!(arg in cache)) {
			cache[arg] = that(arg);
		}
		return cache[arg];
	};
	
};

var cachedSin = Math.sin.cached();
console.log(cachedSin(1));
console.log(cachedSin(1));

var isPrime = function(num) {

	var prime = num != 1;
	for ( var i = 2; i < num; i++ ) { 
		if ( num % i == 0 ) { 
	  		prime = false; 
	  		break; 
		} 
	}
	
	return prime;

};

var cachedIsPrime = isPrime.cached();
console.log(cachedIsPrime(524287));
console.log(cachedIsPrime(9369319));