I just wrote a post about how to make sure that someone using your contact form is human, which utilized a validation image. While this is effective, it requires the user to spend an annoying 10 seconds deciphering the text and typing it in. Web Design From Scratch has a very clever solution.
The trick is to use javascript to make sure that the user is interacting with the form, by waiting for the user to focus or click on the form itself. Once it sees that the form has been interacted with in a human-like way, it sets a flag in a hidden input field. If the person browsing is not using javascript, then a <noscript> tag is used to show a normal CAPTCHA form which is checked by PHP only if the other input flag returned false.
Sure, there are other ways (the “hidden” empty input field) that work just fine, but this is certainly a clever way of going about it. It exploits a real difference between spambot and human.
Web Design From Scratch’s Anti-Spam Method
12:30 am
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