I’ve got a web page that works just fine in Firefox but not in IE 8.  It includes HTML that looks like this:

<a href="#" onclick="myFunc(0);">Call myFunc</a>

and in my JavaScript, it includes something like this:

function myFunc(num) {
alert("got here");
}

In Firefox, clicking on the link displays the alert.  In Internet Explorer, it produces an "Object expected" error.

I did a little poking around and I learned that myFunc is not defined in IE.

<a href="#" onclick="alert("Type is:" + typeof(myFunc));">Call myFunc</a>

produces an alert which says, "Type is:undefined".

I defined the function in a systemConfig Tiddler in my TiddlyWiki, so I thought maybe it was something funky about TiddlyWiki.  It turns out that IE has a quirk, in that global functions aren’t visibly globally by default.  Or, maybe it is that references to apparently global functions are qualified with "window."

At any rate, changing my JavaScript to:

function myFunc(num) {
alert("got here");
}

window.myFunc = myFunc;

resolved the problem.