Firebug says “No Javascript on this page”, even though JavaScript does exist on the page

Question

Why does Firebug say there is No Javascript on this page when there are clearly loads of JavaScript on the page. I even reloaded the page several time to make s

Answer 1

Similar things have happened to me because I forgot to add the closing tag.

DON'T do this:

<script src="some.url" type="text/javascript">

or

<script src="some.url" type="text/javascript"/>

DO this instead:

<script src="some.url" type="text/javascript"></script>

Answer 2

Since Firefox 49.0 and Firebug 2.0.18 the Script panel is broken. This is due to some internal Firefox API changes. And because Firebug is officially discontinued, this unfortunately won't get fixed anymore.

There was also a bug in Firebug 2.0.11 (and below) in combination with Firefox 39.0 causing this problem. This bug is filed as issue 7918.
It happens when the Script panel is enabled and you close Firebug and reopen it.

You can see two related error messages logged to the Browser Console (can be opened via Ctrl+Shift+J or Firebug menu > Developer > Browser Console):

error occurred while processing 'attach: TypeError: docShell is null Stack: getChildDocShells@resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/devtools/server/actors/webbrowser.js:53:7 ...

and

onPacket threw an exception: Error: Server did not specify an actor, dropping packet: {"error":"unknownError","message":"error occurred while processing 'attach: TypeError: docShell is null\nStack: getChildDocShells@resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/devtools/server/actors/webbrowser.js:53:7 ...

Solution:

The only solution until this bug is fixed is to restart Firefox completely.

Answer 3

From firefox 49, the fire bug will be built in and it is called fire-bug next. So the fire bug add on won't work properly and no issues will be solved. So you can use firefox inspector. See here for details information

Answer 4

I realize there are already 10 answers to this question, but in my case none of them helped. I'm running Firefox version 39.0 and Firebug version 2.0.11. The only fix is to completely restart Firefox (i.e. not just the tab or instance with the problem).

Perhaps it's due to Firefox's over-usage of memory, or maybe there's a bug in Firebug. I can't speak to that, but what I do know is it didn't work. I killed Firefox, opened the exact same page again with no changes made and now it works. This has happened to me numerous times and a complete restart always fixes it, but that's the only thing that does.

Answer 5

As mentioned, sometimes there's a Javascript syntax error that invalidates the whole script. But I have also had this, and simply opening up the page in a new tab or window and refreshing firebug (disable, enable) gets the javascript to show up again.