JavaScript file upload size validation

Question

Is there any way to check file size before uploading it using JavaScript?

Answer 1

No Yes, using the File API in newer browsers. See TJ's answer for details.

If you need to support older browsers as well, you will have to use a Flash-based uploader like SWFUpload or Uploadify to do this.

The SWFUpload Features Demo shows how the file_size_limit setting works.

Note that this (obviously) needs Flash, plus the way it works is a bit different from normal upload forms.