Hi,
As to your question:
1. The uploader has a MaxFileCount property. You can set that property to 1 and then user will only be able to submit one file. However this property controls the number of files to be
submitted, not the number of files to be
uploaded. Consider the following sequence:
a. User browses and uploads file a.gif. File "a.gif" appears in the uploaded file list;
b. User deletes "a.gif". Now the file list is empty;
c. User browses and uploads file b.gif. File "b.gif" now appears in the uploaded file list;
d. User submits the page (for example, by clicking another button), file "b.gif" is submitted and your FileUploaded event is triggered;
Here user uploaded two files but only submitted one. Your code will only see "b.gif". In a way, it's like user typed letter "a" in a textbox, then typed backspace to clear it, then typed letter "b", then submit only "b" to you. Generally you should only care about number of submitted files, not number of uploaded files.
2. You will always need JavaScript to handle ClientSideOnError. The question is not JavaScript or not. The question is where you put your JavaScript.
There are a number of ways to put JavaScript in your page. You do not have to put it inside <head>. For example, you can just place it right before the AJAXUploader and it should work for you. For example:
Code: HTML/ASPX
<script type="text/javascript">
function your_error_handler(....)
{
.....
}
</script>
<eo:AJAXUploader ClientSideOnError="your_error_handler" ... >
....
</eo:AJAXUploader>
Hope this helps.
Thanks!