var myModule = function(){
	//Keep the vars outside the global namespace (global vars are evil!)
	var a = 122;
	var b = 22;
	
	return {
		init: function(){
			console.info("The module has been initialised");
		},
		add: function(c){
			//c doesn't exhist so 0;
			c = c || 0;
		
			var sumA = a + c;
			var sumB = b + c;
			
			console.log(sumA);
			console.log(sumB);
		}
	}
}();

myModule.init();//Initialise
myModule.add(33);

Simple illustration of structuring your JavaScript and minimising your use of global vars.

Module layout in JavaScript

module

JavaScript