I am trying to make a simple setTimeout, to make a div tag invisible after 2 seconds.

The setTimeout function makes the div invisible but irregularly, sometimes immediately and sometimes after 1 sec, and so on.

Here is my code:

  function beginTimeOut(){

    t = setTimeout(function(){hideSubMenu()},2000);

}

function hideSubMenu(){
    var elem;
    elem = document.getElementById("ul_navlist1");
    elem.style.visibility="hidden";
    clearTimeout(t);

}

By the way, t is a global variable. I have tried this too: t = setTimeout("hideSubMenu()",2000); but with the same irregular results.