Hi, this is probably quite a basic one, but I'm struggling to get an argument passed in to a function successfully.

When I do this, the code doesn't execute:
Code:
document.onclick = newTarg(5);
document.ondblclick = newTarg(10);

function newTarg(spd) {
	alert('Working = '+spd);
       // More code here
}
Doing this instead works fine:
Code:
document.onclick = newTarg;

function newTarg() {
	alert('Working');
       // More code here
}
Any ideas why it won't let me pass a variable in? I've never really formally learnt Javascript so this is getting a bit frustrating...