gistfile1.js

var decrypt = function(text, key) {
	var src = "abcdefghijklmnopqrstuvwxyz";
	
	var cipher = {};

	for(var i=0 ; i<26; i++) {
		cipher[src[(i+key) % 26]] = src[i];
	}

	//console.log(cipher);

	var output = [];

	for(var j=0; j < text.length; j++) {
		output[j] = cipher[text[j]];
	}

	return output.join('');
};