Firefox “window.event is undefined” error

Question

I have this script:

function postBackByObject(e) {
   var o = window.event.srcElement || e.target;
   if (o.tagName == \"INPUT\" && o.type == \"check         


        

Answer 1

It's possible to pass event object in the inline declaration:

<input type="button" onclick="postBackByObject(event);" value="click" />

function postBackByObject(e) {
    var o = e.srcElement || e.target;
    // ...
}

Answer 2

i am not sure if window.event is supported in all browsers. I think you get event in variable "e" of postBackByObject(e)

Answer 3

Your line

var o = window.event.srcElement || e.target;

fails on all browsers excepting IE, since for them windows.event is undefned

The proper formulation would be :

var o = e ? e.target : window.event.srcElement;

Since standard compliant browsers will pass the event as the parameter e and the target at e.target in IE, e will be undefined and you must use window.event.srcElement

Note that recent versions of IE do support the standards compliant model.

On a more generic note, when you try and access a value as a.b.c.d then a.b.c must be a defined object else you will get the error a.b.c undefined.

Answer 4

That's because it is. window.event is for older versions of IE.

The typical way to do this is:

function postBackByObject(e) {
    e = e || window.event;
    var o = e.srcElement || e.target;
    // ...
}

Answer 5

Pass the event on the onClick event like this:

onclick="myCustomFunction(event);"

It does work and you can access the event object!

Answer 6

You are attaching events inline onclick="postBackByObject();"

Try passing this(the event target) to onclick="postBackByObject(this);" Modify your function to handle this change:

function postBackByObject(e) {
   if (e.tagName == "INPUT" && e.type == "checkbox") {
        __doPostBack("", "");
    }
}

A better alternative will be to attach events using addEventListener

If your markup looks like:

<div id="TvCategories" onclick="postBackByObject(this);" />

then

document.getElementById('TvCategories').addEventListener('click', postBackByObject);

Your postBackByObject function remains unchanged when using this approach.