how to overide something in jquery code example

Example: jquery user function override

function helloWorld (argument) {
	alert(argument);
}
/*Now, if you want to override this function then*/
var origHelloWorld = window.helloWorld;
window.helloWorld = function(argument) {
    	//your code
    	origHelloWorld(argument); 	// after your code if you want to call original function 
}