Are you a smart computer-savvy? Please see if you can help me!

There is a Firefox add-on called “Reload Every” that reloads a page every few seconds. I am looking for an add-on, code, program or whatever that does something more.

I want this add-on to reload the page every few seconds and then checks and sees if a certain phrase appears is in the page. If the phrase appears in the page, then it reloads the page again. If the phrase is not in the page it stops reloading.

I appreciate your help.

Thank You.