Execution order of event-script, content-script and the web page

Add-ons Development
#1

My web page uses my extension which has event-script and content-script. In what order are the three executed?

My web page depends on content-script being available on window.load and my content-script depends on my event-script being available and ready for use. Can I assume the following order of execution for my scripts:

  1. First, my event-script is loaded, it connects to a native host application and it registers chrome.runtime.onConnect listener for messages from content-script
  2. Second, my content-script is loaded and it connects to event-script using chrome.runtime.connect, it also adds window.onmessage listener to receive messages form web page
  3. Last, on my web page in window.onload event I start to send a messages to content script using window.post and get response via window.onmessage
#2

1.) Yes, even though in Firefox they are not event scripts but permanently active background scripts. They lad at the browser start and stay active until the browser is closed.
2.) It depends on the value of run_at in your content_scripts: https://developer.mozilla.org/en-US/Add-ons/WebExtensions/manifest.json/content_scripts
3.) You may want to listen to DOMContentLoaded instead.

#3

Thanks, everything is clear now.