Disable new tabs
Navigate to about:config
This way, whatever link you click that would ordinarily open a new tab will not, so you can see what it does in the network inspector. Then change these settings ...
Extensions you can use with Firefox Quantum: Saka Key, Shortkeys
However any extension seems to be limited and does not work in various situations:
privileged pages such as https://addons.mozilla.org/
new tab page,
internal pages such as about:config,about:newtab,about:addons
outside of the webpage such as in the url bar/ search bar
before the page has ...
Press Esc or use the split console button () to toggle the visibility of the console.
You can use the console alongside other tools. While you're in another
tool in the Toolbox, just press Esc or press the "Toggle split
console" button in the Toolbar. The toolbox will now appear split,
with the original tool above and the web console underneath.
Searching elements by XPath within the DevTools Inspector is only available since Firefox 75. See bug 963933 for more information.
Note that you can also search elemnets by XPath using the command $x() in the console, or use the add-on Try XPath.
You need to prepend a semicolon to the command:
There's more info on that command on MDN web docs.
If the --fullpage parameter doesn't work, i.e. you only get a screenshot of the viewport instead of the whole page, you either typed it wrong or it's a bug. To check whether it's a general bug in Firefox or caused by some setting or ...
The touch event simulation available via currently (as of Firefox 51.0.1) only translates mouse events into touch events.
It doesn't provide mobile gestures like dragging to scroll (bug 1282089), nor shows a circle as cursor (bug 1271728). So, this feature is very restricted at the moment.
I think you are bumping into bug 950732. This was fixed in Firefox 29, which you can get by downloading Aurora.
There are a lot of new features and bug fixes (like this) for web developers that are landing with the latest browser versions, and by using Aurora you can get a chance to use them earlier.
I was actually looking for this feature in Pentadactyl a few days ago, but like Ehvince, I couldn't find it in the documentation. I'm sure a plugin can be written for it, but I tried to find a workaround for now.
The closest I could get was to use extended hint mode to open the context (right click) menu somewhere on the page, and choose "Inspect element" ...
The dark theme you are referring is still there as I see it now.
Go to your FF browser and click: Tools / Web Developer / Web console
On the left hand side, you will find a button named Toolbox Options. whenever you click on it, you will see the theme style chooser. You can choose Dark Theme and it will be changed directly the same as the old one.
(Today) you can find the option you're looking for in the address bar. Just click on the icon beside the shield, it's usually a small lock or a sheet of paper. This opens a small context menu with the option to delete cookies and website data. (Sorry for the German screenshot)
Tested with Firefox 89 Developer Edition.
run on load of the page :
var x = document.getElementsByTagName("BODY");
For your convenience I created a demo that shows the
code in action here.
Click the Run button to see it work.
To learn how to use Greasemonkey, see
The Beginner’s Guide to Greasemonkey ...
Mozilla Firefox seems slow... to... start.
I never saw this notification before with older versions (pre v70.0).
That message has been in Firefox since 2014 (if not longer).
That is a valid message that shows if Firefox starts slow.
Some solutions are in the Firefox takes a long time to start up article
Source I have a message at the bottom of the window ...
Open the Browser Console:
from the menu: select "Browser Console" from the Web Developer submenu in the Firefox Menu (or Tools menu if you display the menu bar
or are on macOS).
from the keyboard: press Ctrl+Shift+J (or
Cmd+Shift+J on a Mac).
In the top right select Requests:
(I use Waterfox so the app icon is different, and I'm using the Dark ...
I would advise you to abandon what you have been doing so far, and learn to use Selenium.
Selenium is pretty much industry standard, when we are testing web apps, and allows you to automate (script) browser interaction.
Selenium automates browsers. That's it! What you do with that power is
entirely up to you. Primarily, it is for automating web ...
This feature is now available in beta version (v67.x). You will need to go to about:config and enable the flag devtools.netmonitor.features.resizeColumns.
For previous versions see Change columns size in Firefox Developer Tools
The Firefox DevTools provide different kinds of sticky and non-sticky highlighters.
The one you might be looking for is to highlight all elements matching a specific CSS selector, which can be toggled via the "target" icon besides each selector within the Rules side panel of the Inspector:
The Firefox DevTools don't have a way to apply a change to a website everytime the page loads.
If it's really just some layout change, Stylish is the right add-on to use. And if the change also relates to functionality, a GreaseMonkey script is the way to go.
If you're using Firefox 52 or later and need to switch back to the old Debugger, you can do so by visiting about:config and setting the devtools.debugger.new-debugger-frontend preference to false as explained on MDN.
The Firefox DevTools do not offer this feature yet. There's an enhancement request filed for it, though.
Until the feature is available within the tools, you can mimic its behavior by setting a breakpoint and then continuing the script execution, as DavidPostill wrote.
Hit F12 to pop open the developer tools menu and go to the Storage tab. You'll be able to view and delete the Cache Storage, Cookies, Indexed DB, Local Storage, and Session Storage for the domain of the page you're currently on.
Time to refresh the answer.
The official support page now is good enough and also points to a new extension to customize kyeboard shortcuts called Saka that's experimental but kind of official and works great for me (Firefox 60 developer edition / Ubuntu Linux)
actually the Customizable Shortcuts Extension is able to change firefox shortcuts (and potentially show conflicts); you should give it a try.
However i'm still looking for a extension-less solution and the ability to totally disable a shortcuts...
As @louis noted, the customizable-shortcuts add-on has been discontinued (around 2016/2017).
The sames ...