From your comments:
The original question was, in fact, asking for a library recommendation. The first edit changed this entirely. The second edit made some assumptions about the situation where the OP would want to grab file sizes.
The first edit was good.
Library recommendations aren't on topic here! However, the question was describing the step, not the goal. The thought process was roughly:
- I want to find out the size of a file in IE 8/9.
- I am sure I can do it with a library of some sort.
- The question: Are there any libraries for checking file sizes in IE 8/9?
This still preserves the actual problem the asker is trying to solve. It is even an improvement on the question, considering the asker shouldn't have been asking about the step in the first place: what if there isn't a library, but there is a solution?
The second edit was not.
I agree with you on the second edit. It ought to be rolled back, as it introduces new information that doesn't appear to come from anywhere. The asker never hints at form submission in the original.
The asker does mention uploading and validation, but the same could be done entirely through means such as an AJAX request with no forms involved at all.