title: Detect CSP violations with javascript
body: <p>Is it possible to detect a Content Security Policy violation with javascript?</p>
  
  <p>My CSP works and sends its reports, where I see that some urls are injected, probably by browser addons. I would like to display a hint to the user, that some addon tries to modify the page.</p>
  
  <p>Can I somehow detect the aborted connection with javascript (which is itself whitelisted in the CSP of course)?</p>