How to get the caller event and dom element id

Answer 1

An event object is passed to the Hello function automatically. You need to receive it as an argument and then do some cross-platform work to grab the element. A JS framework will help you out here.

function Hello(e){
    var caller = e.target || e.srcElement;
    console.log( caller );
}

EDIT
+1 Andrew's comment below. Use addEventListener and attachEvent for best practice.