If e.preventDefault(); is not working you must use
e.stopImmediatePropagation(); //instead.
For further information take a look at: What’s the difference between event.stopPropagation and event.preventDefault?
$("#mainTabs a").click(function(e) {
e.stopImmediatePropagation();
});
If you’ve attached other event handlers to the link, you should look into e.stopPropagation() and e.stopImmediatePropagation() instead. Note that return false is equivalent to calling both event.preventDefault() and event.stopPropagation().