Form Text Field - Require .mp3

Hi There Everyone,

I have a form text field that I want to validate to contain a certain set of text at the end.

The field allows people to enter the URL of an MP3 file, so the field needs to check that the inputted text ends in “.mp3”.

If the field dosen’t end in “.mp3” it should pop up a message saying something like “please check your field ends in .mp3 and try again”.

The field should also be required.

Can someone please tell me how I would accomplish this?

Thanks
Zach

I had found this tutorial previously but wasn’t entirely sure how to implement it.