Thread: Blocking Spam With Javascript

Hi all,

Coder Will Bontrager (willmaster.com) shared this spam busting tip with me, and I thought you might find it useful.

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One of the easiest form spam reduction techniques is to put a URL in the form's action tag that goes to a regular page instead of the form handling script - a real page, not a 404, so spammers don't get notified to manually investigate your code.

Somewhere below the form, JavaScript assigns the correct URL to the action tag.

The form tag needs an id value for the JavaScript to use. Example:

<form id="handle" action="/index.html"> ... </form>

<script type="text/javascript"> document.getElementById("handle").action = "/script.php"; </script>

Spammers' robots seldom parse JavaScript, so their automated submission never reaches the form handler specified by the JavaScript.

Instead, their spam goes poof at the URL hard coded into the form tag.

It's a lot easier to just use a type="button" instead of a type="submit", then use the onClick of the button to go to a function that submits to the real page - the address of which is generated in pieces by Javascript. Why rewrite the document?

Most of this spam blocking is done server-side now. The host's server should usually have this built in and this Javascript isn't that necessary in this day and age.