Limit number of selected files when multiple is enabled

[wanxie]

How do I limit the number of selected files?

What I want is to limit 2 files and when user selected 3, alert a message and do nothing afterward. I tried to use onfileadd to alert the message but it actually call alert 3 times, one for each files. I only needed one?

Also, is there a way to call upload only once for all files instead call upload for each file in onfileadd? Example would be using onchange event of the html file input.

Thanks

[tim-evans]

I'm not sure if this is possible for the selection. :/