Defining and calling function in one step

You can try:

(window.powers = function(i) {
  /*Code here*/
  alert('test : ' + i);
})(2);

<a href="#" onclick="powers(654)">Click</a>

Working link : http://jsfiddle.net/SqBp8/

It gets called on load, and I have added it to an anchor tag to change the parameter and alert.