Anti-Spam using Captcha

Reduce Spam using CAPTCHA

Using CAPTCHA techniques to stop spam

Note: This form does not submit any data to anywhere. It is for demonstration purposes only.

This form uses both FrontPage JavaScript validation and server side scripting to check the Captcha device. The client side (JavaScript) check is not effective if JavaScript is disabled.

The JavaScript validation checks that the text box near the image contains the digits depicted in the image. This check will fail if JavaScript is disabled, as is the case with some spambots. A more effective method is to validate the field on the server. This page emulates Disabled Javascript.

Note that using an image has accessibility issues, unless an alternative (not used here) is provided for those users with images disabled (screen readers etc.)

See wikipedia.org/wiki/Captcha for more information.

This example uses a single image to determine if the form-filler is human or machine. If the digits shown by the image are entered incorrectly, the message is not sent. In this demonstration, if the digits are wrong, an alert is given - but, in a "real" form, unlike here, no indication of failure should be given to the user.

This page shows what happens when JavaScript is enabled. JavaScript disabled version

Anti-Spam using Captcha

Reduce Spam using CAPTCHA

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