在上传之前显示文件大小...？

Question

I need the php to work with javascript... :|

I want the user to upload only max 5MB files, but PHP detects it only after the upload is done... example:

if ($_FILES["ftu"]["size"] > 5242880) {
        echo "<br /><font color='#FF4747'>Sorry, but maximum size of the uploaded file must not exceed 5MB</font>";
}

It works, but it echoes only after the file is actually uploaded... and I don't want it... Another option is to check it with javascript:

$(document).ready(function(){
        $('#upheadinp').bind('change', function() {
            if(this.files[0].size > 5242880){
            $('#uploadspan').html("<font color='#FF4747'>Max file size is 5MB</font>");
            }
        });
    });

Yeah so this works too, but it's only to show the error message... How could I merge php if function with this javascript function ?

My expectations are something like:

<?php
if("<script>(this.files[0].size)</script>" > 5242880){
echo "error";
}
?>

Could someone help me out? Thanks!

Answer 1

The above comments are obviously correct. JS is a client-side scripting and PHP is server-side. The two do not directly interact for obvious reasons.

The best solution would be to prevent the form from being able to submit. This would achieve what I interpret to be what you are looking for. A way to prevent someone from submitting in addition to the PHP prevention. Proper programming convention would dictate any user submitted data (text, uploads, etc) should be validated both on the client and server ends. Never trust client data and never assume it was properly validated.

$("theformyouareusing").submit(function(e) {
    if($('input[type=file]').files[0].size > 5242880){
         e.preventDefault();
        }
    });

You may also want to have a check for older browsers that do not support .files.size and decide how you want to handle those cases.

For additional security, you should add these lines into your php.ini:

post_max_size = 5M
upload_max_filesize = 5M