title: How to send an alert in chrome extensions?
body: <p>I am trying to get some experience with chrome extensions. I have a question though. Let's say I am writing an extension that everytime you see the word (wow) in the url, i will alert the user with a red page that they have to click on accept to pass, or an alert box that they have to get through in order to see the page, how would i:</p>
  
  <p>1) get the url of the page
  2) make the red alerting page, or the alert box without the need for the user to actually go click at the extension's icon to get information?</p>
  
  <p>Thank you so much</p>