How to apply event.stopPropagation?

Let me explain the problem first. I am using the following UL structure:

<ul onmouseover="smenu_over(this)" onmouseout="smenu_out(this)" class="sub-menu" style="left:0;">
            <li><a href="#">Navigation Item with long text do text wrap</a></li>
            <li><a href="#">Sub nav item</a></li>
            <li><a href="#">Sub nav item</a></li>
            <li style="border-bott开发者_运维百科om:0;"><a href="#">Sub nav item</a></li>
          </ul>     

JS Function

function smenu_over(obj) {
  var a = obj.parentNode.childNodes[0];
  if(a!=null) {
   var top = $(".topnav_icons").length && !$(".logo_t").length ? "-45px" : "-34px"; 
   setBckPosition(a, top);
   a.style.color = "#fff";
  }
 }    

I need to apply the event.stopPropagation inside this function which is called when mouseover event happen.

Please help me the code to apply event.stopPropagation?

You mean this:

$('ul.sub-menu a').mouseenter(function(event){
   event.stopPropagation();

   // your code....
});

You can remove your current handlers from being in-line, like this:

<ul class="sub-menu" style="left:0;">

Then you can bind these functions in jQuery, like this:

$(function() { //run when DOM is ready
  $("ul.sub-menu").hover(smenu_over, smenu_out);
});

In your functions, instead of obj just use this, it'll refer to the element you're hovering, like this:

function smenu_over() {
  var a = this.parentNode.childNodes[0];
  if(a!=null) {
    var top = $(".topnav_icons").length && !$(".logo_t").length ? "-45px" : "-34px"; 
    setBckPosition(a, top);
    a.style.color = "#fff";
  }
} 

The important difference here is .hover() maps to the mouseenter and mouseleave events (not mouseover/mouseout), which don't fire on the parent when entering/leaving a child, so no need to stop propagation, they already behave like you want.

You can probably optimize this much further, but without seeing your other code I don't want to give you any bad advice, this will fix the current issue though.