How can I know which html element clicked

function someClickHandler() {
   // do something
}
function someOtherHandler() {
   // do something else
}

oneElement.onclick = someClickHandler;

anotherElement.onclick = someOtherHandler;
// you can reuse the same handler for more than one element,
// depending on what you need

// do this little experiment:

oneElement.onclick = someClickHandler; // yes, it will work even if the 
// handler is not yet defined; want to know why? :-)
function someClickHandler(ev) {
   if (ev.target === oneElement)
       alert("you passed reference to the element clicked");
}
// use it the way you want