Frank WisniewskiIt happens again and again that inexperienced users want to upload unnecessarily large files to the server.
With this little onchange oneLiner you can check that before uploading.
Use data-mfs=.... (....=fileSize)
<!DOCTYPE html>
<html lang=de>
<head>
<meta charset=UTF-8>
<title>Document</title>
<h1>check max filesize</h1>
<form>
<input type=file
name=filename
data-mfs=100000 onchange="this.setCustomValidity(this.files[0].size>this.dataset.mfs?'to big!!':'')"
required>
<input type=submit>
</form>
