I started having a strange error on some pages. The website has been working fo the last 3 years with no problem. We sell IT courses and have pages for both individual and group registration. Group registration stopped working lately.

see page:


Insert any number greater than 1 and click "Avanti" (next) to simulate a group registration.

Then on the registration page click "Avanti" again. This should call a function called "checkData()" to...well, check the data in the form.

If you use inspector/devloper tools you will see an error

"ReferenceError: checkData is not defined"

But the checkData is in the page. Why this behaviour or conflict?

1 Answer 1


Well, "checkData is not defined" isn't your only problem. Your page by the time of loading produces js errors. Also, when you focus in your input field there is one more error.

By the way, submitting in your form, it goes on -while trying to enter a number higher than 10, it reports back the restriction that I can only register up to 10 persons. I didn't get the checkData is not defined.

I don't know what is the expected behavior when submitting in your form, nor I spent much time to test further. But one important thing I quickly noticed is that you are loading more than one instances of the jQuery library in your page and in most cases this is enough for creating all kind of js errors.

You may also find some helpful tips here: Javascript errors in console - jQuery Easy - JCH Optimize

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