[Javascript] Avoid multiple onclick

[javascript at webdesignofficina.com (Guillaume)]

Hi there,

I'm using onclick events to fire some functions. Such as:

var oncL2 = document.getElementById('shOptNav');

oncL2.onclick = function() {checkOptSliD(); clearMt()};



Trouble comes when a user clicks several times, the functions are fired 
each time, added to each other...
This is an issue since I'm using some loops to check some elements 
dimensions. These loops are then added into memory each time the onclick 
event fires causing memory overload...

So what I'd like is the functions to fire only once even if onclick is 
performed multiple times.

How do I do that ?

Thanks.

Guillaume