Why doesn't 'event ' work in firefox browser?

JavaScript
1

I am writing a simple javascript code to capture which element raised an event. When I run this code it works okay in IE. But Firefox says ‘event’ not defined.

Also I am using Microsoft Visual studio 2008 to create this file. And for somereason, there is no context sensitive help when I am using event object. Why is that?

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Javascript_CreateaDynamicTable.aspx.cs" Inherits="FHLBSF.QRMDMS.WebUI.Javascript_CreateaDynamicTable" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <img alt="" src="media/fhlbsflogo.gif" />

  <p style="position:absolute;top:10;left:10;color:black" onmouseout="OnMouseOut()" onmouseover="OnMouseoverEventHandler()"> Demo of "OnMouseOver" handler</p>

 <table border="1">
  <thead>
    <tr>
      <th>Month</th>
      <th>Savings</th>
    </tr>
  </thead>
  <tfoot id="tfootelement" onmousemove="WhichElementIsThis();">
    <tr>
      <td id="tdSum" onclick="WhichElementIsThis();" >Sum</td>
      <td>$180</td>
    </tr>
  </tfoot>
  <tbody>
    <tr >
      <td>January</td>
      <td>$100</td>
    </tr>
    <tr>
      <td>February</td>
      <td>$80</td>
    </tr>
  </tbody>
</table>

 </div>

    </form>
</body>

<script type="text/javascript" language="javascript">

            function WhichElementIsThis() {



            var varElementId = event.srcElement.id;

            alert(varElementId);



        }

   </script>


</html>
2

There are two ways to access the “event” object, based on the browser (some browsers might support both, I can’t remember). One way is the global “event” object, which IE6-8 supports and which you are using.

The other way to do it is assume that the event object has been passed to the event handler, like this:


function WhichElementIsThis(event) {
    // ...
}

Certain browsers (Firefox, Chrome, IE9) will automatically pass the event object to your function. So for cross-browser compatability, you could do something like this:


function WhichElementIsThis(event) {
    event = event || window.event;
    // ...
}
Off Topic:

Another cross-browser issue you’ll run into is that not all browsers support the ‘srcElement’ property; some use ‘target’ instead, so you’ll want to do this, too:


function WhichElementIsThis(event) {
    event = event || window.event;
    var elem = event.target || event.srcElement;
    // ...
}