Why can't the upload field select a new file after jQuery-validate returns an error?

I'm coding a form using PHP and jQuery. I have a file upload field to which I applied the following jQuery-validate rules:

image: {
 accept: "jpeg|jpg|png|gif",
 required: "#edit_ID:blank"
}

The file upload field must only accept jpeg/jpg, png, or gif images. It is required only if the field with开发者_JS百科 the ID "edit_ID" is left blank.

This is my file upload field:

<input type="file" id="image" name="image" class="input1" />

The file upload field selects files without any problem, but when jQuery returns an error because of a violated rule, even if I select a new file from my computer the file I selected before the error appeared remains there. It's as if it becomes disabled after jQuery-validate gives an error.

I tried removing the rules set for this field, tested it, and encountered no problem.

Does anybody have an idea what's causing this problem?

Thanks.

P.S.: I encounter the problem in Firefox (v.3.6.9) and IE (v.8) but not in Google Chrome (v.5).

This will not answer your original question, technically.

But, it's not a good idea to trust client side programming to do image validation; your program can be fooled. Since you are using PHP anyway, why not use PHP to do some server side validation?

All files uploaded are stored in the $_FILES array. You can check file type like so:

<?php
    foreach($_FILES as $file)
    {
        if(!empty($file['type'])) //only check if there's a valid file type
        {
            if($file['type'] != 'image/jpeg' && $file['type'] != 'image/png' && $file['type'] != 'image/gif')
            {
                //this file is not any one of the accepted formats, so long!
            }
            else{//do your processing}
        }
        else{//error invalid file}
    }
?>

In case you want instant validations, you can still use AJAX, instead of relying solely on the client side to do the validation.