I have a simple jQuery script. This is the script:

```
var menu = $('#nav .menu');

$('li', menu).mouseenter(function() {
    $(this).find('.sub-menu').slideDown();
}).mouseleave(function(){
    $(this).find('.sub-menu').slideUp();
});

```

This script open a submenu. But i have a problem with this script. If you go over it quickly. The script launch every time. When you go over the item verry quickly. The menu open a lot of times. How can i fix this?

Thank for help