Javascript in forms

Hi!

I want to modify the javascript validation on my own WWF forum, and would like a certain field to be checked for the caracter in quotes ( " ), as it is messing up my database, what do I then change???

ex.

I would like the field xxx to he checked for illegal sign = "

 //Check for this -> " 
 if (document.form.subject.value==""){
  errorMsg += "\n\tXXX \t\t- The " is NOT allowed!!!";
 }

Please help! :O)

Thank you!