Not empty TextArea
<html> <head> <script language="JavaScript"> <!-- function validateForm(f) { if (f.value == "") { alert("Please enter some text into the feedback field"); return false; } else return true; } //--> </script> </head> <body> <pre> <form name="myForm" method="post" action="http://www.java2s.com" onSubmit="validateForm(myForm.feedback)"> Full Name: <input type="text" size=30 name="persons_name"><br> Feedback : <textarea name="feedback" rows=5 cols=50></textarea><p> <input type="submit" value="Send Data"> </form> </pre> </body> </html>