Installing Firefox the following way has one advantage: Firefox will update itself automatically as soon as an update is available. This is great for users, who want to get the latest update as soon as possible without waiting for the next Manjaro update. It is also great for systems which need an updated (i.e. secure) web browser but are updated rarely.

1. Find out, whether your Manjaro installation is 32bit or 64bit:

uname -m

If the output is x86_64, you are using a 64bit installation of Manjaro. If the output is i686, your Manjaro installation is 32bit.

2. Download the latest Firefox in your language from here: https://www.mozilla.org/en-US/firefox/all/

Download "Linux", if you are using a 32bit installation of Manjaro or "Linux 64-bit" if your installation of Manjaro is 64bit.

3. Unpack/extract the downloaded firefox-xx.x.tag.bz2 file to

~/bin/

This is the default path this wiki page will use in the continuation of this tutorial. When you want to use other file paths you have to adjust this tutorial, too. An alternate file path of your home directory is the following (please replace <YourAccountNameHere> with your account name):

/home/<YourAccountNameHere>/bin/

If a bin folder in your home directory does not exist, create it.

If a visible bin folder in your home directory bothers you, you can use a hidden .bin folder instead:

~/.bin/

Most file managers make hidden files visible by pressing CTRL + H.

You can now start to use Firefox by double clicking on the file (or executing it in a terminal):

~/bin/firefox/firefox

4. Let's create an icon in order to start Firefox much more easily: create an firefox.desktop file and edit it:

sudo kwrite ~/.local/share/applications/firefox.desktop

(Instead of kwrite, use your preferred text editor: e.g. leafpad, gedit, mousepad, juffed, etc.)

Copy and paste the following code into your firefox.desktop file and save it:

[Desktop Entry]
Name=Firefox
GenericName=Web Browser
Icon=~/bin/firefox/browser/icons/mozicon128.png
Type=Application
Categories=Application;Network;WebBrowser;
Exec=~/bin/firefox/firefox
Terminal=false
StartupNotify=false

Now, you can click the firefox.desktop file and your Firefox will start. Create links of your firefox.desktop file or copy it to the place you prefer. You should also be able to start Firefox from your start menu now (after a reboot of your system).

More

This method works for firefox-betaand firefox-aurora (The aurora channel got replaced with Firefox Developer Edition recently), too. Unfortunately, Firefox' own updater does not update to the next major version (e.g. from Firefox 33.0 to Firefox 34.0) for all these pre-stable releases of Firefox. The next major version needs to be downloaded and unpacked/extracted manually every time a new major update of Firefox is released.

Edit: Sometimes, the update to the next major version works, but with a slight delay. Please test for yourself.

This post is based on the following sources:

There is a forum entry for this post: https://forum.manjaro.org/index.php?topic=16246.0

More Tips about Firefox in the Manjaro Wiki are available here