When I view my extension with the developer tools, I only see the generated background file, background.js; my content script doesn't appear under the content scripts tab. Any ideas why? The relevant part of the manifest looks like this:
"content_scripts": [{
"run_at": "document_end",
"js": ["postMsg.js"],
"matches": ["https://groups.google.com/forum/*"]
}],
postMsg.js gets injected into the page, but never appears in the developer tool window, so I'm unable to debug it.
As long as you are on a page that matches the "Match patterns and globs" from your manifest, you will see the content script(s) under the Sources -> Content Scripts pane.
You may need to refresh (F5) the page (and/or your extension, then the page) to see it:
For more information on matching that cryptic number to an extension, see this answer.
content scripts as a js file are never exposed by pages which are injected.. If your intention is debugging of content scripts it can be possible;
Ex:
mycontentscripts.js
var getStyleofbody = document.getElementsByTagName('body')[0].style;
to debug this i would first run this code in console of page that i am going to inject; After i get expected results i will move code to contentscript js file.
However for any errors after injection you can look at developer's console panel for all errors(they are listed there).
Let me know if you are confused
In 2018, if for some reason you've missed it:
Press the >>. From there select content scripts, and you'll be able to see the content scripts.
hf :)
来源：https://stackoverflow.com/questions/13577330/unable-to-view-content-script-references-in-the-developer-tools-window