I’m not sure why this was previously overlooked in HTML4/XHTML1, but it’s been a real pain for developers for years. The ‘rows’ and ‘cols’ attributes are useless (like ‘size’ is in the INPUT tag) as they are based on display size of fixed-width fonts like Courier and not the actual input limitations. INPUT has always supported a ‘maxlength’ attribute for this purpose.
Good news, this is part of WebForms2 and HTML5 (proposal) plans to add it!
A decent fix that I currently use… optimally you would use a common ‘maxsize’ function.
[textarea name=”junit” id=”junit” onkeyup=”maxsize(this,100);”][/textarea]
You should ALWAYS perform server-side validation of the length too, otherwise you leave the door open for someone to hack your form and submit longer data.