How to connect with other third party API?

We would like to connect with another third party API for verifying data which was entered in the form in real time.

Can we include code in any submit button for doing a query o execute java script code?

Hello There!

Thank you for your message.

In this particular case, in order to add JS code, it is necessary to get the source code of your form and add it to a website page, you can follow the steps here https://www.jotform.com/help/104-how-to-get-the-full-source-code-of-your-form.