i had developed a registeration application where i used captcha image for secuity code image . i stuck up with validation for the strings in that image to my text box i had enter.can anyone tell me how to do validation using javascript in that?
Security is to be validated at the server side, period.
Captcha is just a security technique. That you're using it the wrong way, doesn't make it a bad solution.
As said, just submit the form to the server, let the server validate the captcha and take action accordingly.