file upload using progress element in HTML 5

I am using progress element while displaying the progress of a file upload in javascript. But the problem that I am facing is it is not completely loading huge file.when I c开发者_Go百科hecked evet.total attribute it gives the total size of the file in bytes.But when it loads physically event.loaded attribute loads only 70 to 75 %.So I want to know is there any pre-requisite when use progress event? Has anybody faced this kind of issue before?.Thanks in advance.

Are you use a FileReader to upload the file? If you are, you can define the .onloadend method of your FileReader which will trigger when the file is done reading.

Read the docs here: https://developer.mozilla.org/en/DOM/FileReader

There is a ticket raised as bug in FireFox.The details as follows: https://bugzilla.mozilla.org/show_bug.cgi?id=641287