Of course there is nothing wrong if you implement onChange event using the traditional way, that is by adding onchange=”" attribute to the HTML element. However, your codes can be better in some ways if you do it using jQuery.
When I was developing theme, I found a weird problem in IE8. This is the case: I have a DIV that has opacity of 0.4. When I use $(elem).css(‘opacity’) to get its current opacity, it works fine in all browser except IE8, which return opacity of 1.
If you tested your page using FireBug in Firefox and found the error "$ is not a function" or "$ is not defined", most likely you are using other libraries in your page. Libraries that conflicts with jQuery includes MooTools, Prototype, etc.
I used to load jQuery library via Google AJAX Libraries API to save my bandwidth. It works in all browsers at the beginning, including Internet Explorer. However, it suddenly failed to load in Internet Explorer 6 since last week (error message tells me that jQuery is not loaded at all).
If you noticed my tweet, I started to learn jQuery few days ago because I need it to create a photoblogging theme. To test my understanding I need to try making something, so this is the outcome : a tabbed menu script.