Okay, here's my problem. I wrote some JavaScript for a page, for some reason the page doesn't work in Chrome. The site does what I expect in Opera, Chromium and Firefox. In the Choom devtools there is a kind of error showing in the source tab showing "JavScript is disabled" in a mouse hover popup:
I turned off all chrome's extensions, Javascript in on in the content settings and I cleared all JavaScript exceptions I had, but this didn't seem to change anything. The weird thing (an other one) is that some other sites give the same alert icon in the devtools (including this one) but JavaScript works just fine.
If you perform the exact same functions in the console then, some of, the functions perform just fine.
Does anyone have an idea what I could be because I am out of idea's and it is really annoying that I have to switch browser to test the page (page is 'live' here). Thanks
Have you checked the DevTools settings? You might have accidentally enabled "Disable Javascript"
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 sure but it still show the same message.
It never used to do that before, but all of a sudden it misbehaves.
Is it because of some configuration issues or because of something else?
As of Firefox version 50, it seems that Firebug will no longer work as Mozilla are migrating to Firefox Devtools. The tab Tools/Web Developer has a 'debugger' option. See this page for a discussion on the migration. Read all the posts dated 19 November for further information.
It seems to me that the option gives less functionality but Firebug per se is never going to be fixed for Firefox 50 and beyond
EDIT 2017 April
This answer is now outdated and I'm not even testing it anymore because I'm no longer using Firebug (a shame, I loved it years ago in a time it was The tool of trade for web developing).
EDIT 2014 November
The original answer is now more than a year outdated due to firebug evolution.
Thanks to #AmadeusDrZaius to keep it on tracks
Answer for outdated firebug versions
For anyone still with this problem after updating Firebug.
Just click Clear Activation List option inside the Firebug menu.
For those who can't find it, note that "Clear Activation List" shows up in the dropdown from the Firebug icon in the toolbar, but not the Tools > Web Developer > Firebug menu.
I guess due to the bug previous hitting your working page it stays listed as "no activate FB for this site please".
I encountered No Javascript on this page after upgrading Firefox to ver 50.0, with Firebug ver 2.0.18. I tried refreshing Firefox, even completely uninstall Firefox and installed again. Nothing works for me.
A couple of hours later, I downgraded Firefox to 49.0.2, and voila, it works right away. I downloaded the old version here.
I tried everything on this list and nothing worked for me except resetting Firefox like so:
https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-problems
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.
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.
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>
The same problem just happened to me. I thought that it was a problem in my scripts, but I checked google.com and the problem persisted.
My problem was that I had updated my version of FF and kept the old version of FireBug. When I updated FireBug and everything was solved.
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
If the problem only shows up on a single page, check that your script folder is referenced from current folder (".") or that's reachable from the server root ("/").
<script src="./scripts/pagescripts.js" type="text/javascript"></script>
may not be the same as
<script src="/scripts/pagescripts.js" type="text/javascript"></script>
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.
One time this caught me out was when I published one of my sites and I was checking it out. No Javascript was working, there were no errors in the console and firebug showed no scripts.
It turned out that in that instance, I'd forgotten to allow the site in NoScript - so there really were no scripts being loaded.
Not sure if that's the problem you're facing but it's worth being aware of.
I also got this error when attempting to use Ajax to a different server than the one serving up the page. JavaScript only allows Ajax access to the server that served up the page.
This problem is STILL happening (Aug 2015) with Firefox 39.0.3 and Firebug 2.0.11
For people saying the code is wrong or missing end tags etc. all I did to get all the javascript to reappear in tab was to shut down Firefox and restart it. I didn't change anything. Also that "Clear Activation List" option didn't work (no idea what that means)
I upvoted #Tom_Thomson's answer above, but I am wondering if simply removing and then reinstalling the Firebug add-on might not have accomplished the same thing without losing all the other stuff like bookmarks.
FWIW this problem is still happening in August 2016. I'm using Firebug 2.0.17 with Firefox Dev Edition 50.0a2.
As a workaround, I'm able to use the Developer Tools, though they are not as robust as Firebug (when it's working).
Well Firefox native Inspector is good... I know that you will miss some things, but in general we can survive with it. The good news is... less one addon, FF will be faster :)
This might sound crazy but is there a debugger out there which automatically breaks on the first line of executed code ?
Sample : suppose I have debug mode on and I click on a button. Now the intelligent debugger should automatically set the breakpoint on the first line inside the .click({}) function.
This way it is very easy to see the starting point and very easy to backtrack.
There must surely be something.
Thanks
Most debuggers in the browser allow you to insert the keyword
debugger;
into your code which will cause a break to occur at that point in the execution.
Chrome with CTRL+SHIFT+J. ;) You can put breakpoints there. I think it also works under FF. Also new versions of IE have JavaScript debuggers (don't remember the shortcut though).
F12 in most browser opens the debugger.
Chrome, Safari, IE have this by default, and for FF there is the Firebug add on.
Also you can debug from visual studio, select debug from the menu --> Attach to process and then select the interter explorer process. But You should enable the script debuging in Internet Explorer first.
I recently switched from Firefox to Chrome and I (probably) missed an important feature. I was used to test javascript snippets on FF from within the Firebug console this way: open the console, write the script and finally press CTRL + Return to execute the code.
It seems not possible to do the same in Chrome console, as when I type some code there and press return to start a new line the code is executed immediatly.
Is there a way to replicate the Firefox behavior on Chrome?
Thanks.
It seems that there is no explicit “multiline mode”.
But you can:
Paste code (it will preserve multiline)
Shift + Return to add a new line without executing the script
Related bugs:
https://bugs.webkit.org/show_bug.cgi?id=30553
http://code.google.com/p/chromium/issues/detail?id=72739
You can also hit Shift + Enter to start a new line without running the code in Chrome's console: https://developers.google.com/chrome-developer-tools/docs/tips-and-tricks#multiline-commands
Install Firebug Lite for Google Chrome. It has got a console.
Don't look for a full fledged Firebug. You will be disappointed :)
Oops,I didn't read properly at first. My bad!
In Firebug Lite, take Console. Then you will see a tiny red up-arrow at the right corner.
Click on it and you will get a multi-line console. Won't you?
I recommend this:
Write debugger; and hit Enter, in the console tab
This takes you to the Sources tab; if not, make sure debugger breakpoints are active
Now you can write whatever you want in the Sources tab, which acts like a full IDE with features like newline and indentation
Select any part of your code to run, and right-click, choose Evaluate in console
Better way of doing this using Chrome featue i.e Snippets where you can write javascript and save it in chrome developer console.
Its available underneath source inside developers tools while inspecting element.
More info about the snippets can be find on this link.
It was available in Chrome canary and I guess now it is available in default chrome browser also.
Firebug looks not capable to check js syntax error...
Is there any good way to do that?
Currently I just wrote a js but the firebug didn't show any error but the functionality is totally broken.
Firebug does do it. Make sure that you have JavaScript Console enabled, you can do so by clicking the Console dropdown and from their select Enabled. You need to press F12 key to open firebug and once you refresh the page, you will see any errors you have in your script in the firebug js console.
If you are using Firefox, you can also press Contr+Shift+J to open firefox's error dialog.
are you sure Firebug is turned on? If it's on, the little bug in the lower right is colored brown. if it's not on, the bug is gray.
also, I find that Web Inspector in Safari/Chrome is better.