When comparing Emacs vs Codeanywhere, the Slant community recommends Emacs for most people. In the question“What are the best JavaScript IDEs or editors?” Emacs is ranked 8th while Codeanywhere is ranked 14th. The most important reason people chose Emacs is:
Emacs can be controlled entirely with the keyboard. While true, I often find the mouse and menus handy for those lesser-used commands. An aide-memoir.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Keyboard-focused, mouse-free editing
Emacs can be controlled entirely with the keyboard. While true, I often find the mouse and menus handy for those lesser-used commands. An aide-memoir.
Pro Total customizability
Customizations can be made to a wide range of Emacs' functions through a Lisp dialect (Emacs Lisp). A robust list of existing Lisp extensions include the practical (git integration, syntax highlighting, etc) to the utilitarian (calculators, calendars) to the sublime (chess, Eliza).
Pro It's also an IDE
You can debug, compile, manage files, integrate with version control systems, etc. All through the various plugins that can be installed.
Pro Free
Licensed under GNU GPL.
Pro Self documenting
Emacs has extensive help support built-in as well as a tutorial accessed with C-h t.
Pro Works in terminal or as a GUI application
You can use Emacs' command line interface or graphical user interface.
Pro Great documentation
With 30+ years of use the Emacs documentation is very thorough. There are also a lot of tutorials and guides written by third parties.
Pro Ubiquity
Fully compliant GNU-emacs is available on many platforms, and they all understand .emacs configuration files.
Pro Lisp customizations
With lisp customization, any behavior of Emacs can be changed. Update with pre-release patch can be also applied without recompiling the whole Emacs.
Pro dabbrev-expand (Alt-/)
Dynamic word completion.
Pro Provides org-mode
Advanced planning and publication which can start as a simple list.
Pro Mini buffer
You can pass complicated arguments in the mini buffer.
Pro Enormous range of functionalities (way beyond simple "text editing")
Through its programmability, a very broad range of functionalities can be integrated in emacs, turning it even into a "single point of contact" with the underlying operating system.
Pro Rectangular cut and paste
Emacs can select rectangularly.

Pro Vi keybindings through Evil mode
Evil mode emulates vim behaviors within Emacs. It enables Vi users to move inside the Emacs universe.
Pro Has been widely used for a long time
The first verion of Emacs was written in 1974 and GNU Emacs in 1984.
Pro Visual selection and text objects with Evil
Evil is an extensible vi layer for Emacs. It provides Vim features like Visual selection and text objects.
Pro Support multi-line editing, multiple frame, powerful paren, crazy jumping style
Review the "Emacs Rocks" video.
Pro Cross-platform
Works on Linux, Windows, Macintosh, BSD, and others.
Pro Integrates planning in your development process
You can jump straight from your org-mode files to programming tasks - and back - and build a seamless workflow.
Pro Helm plugin adds even more power to Emacs
Powerful commands, search, and more with the Helm plugin.
Pro Versatile
Emacs is great for everything.
Pro GTK+ widgets support
Since version 25 you can run GTK widgets inside Emacs buffers. One of these is the WebKitGTK+, which allows the user to run a full-featured web browser inside Emacs with JavaScript and CSS support among other things.
Pro Excelent tutorial to get you started
The tutorial you are presented with at startup shows you exactly what you need to get started and teaches you how to use the built-in help yourself later.
Pro Interactive Shells
Emacs has a number of shell variants: ansi-term, shell, and eshell.
Pro Gnus
Managing several large mailing lists has never been easier using Gnus. The threading commands and the various ways of scoring articles means that I never miss important messages/authors, etc. A joy to use.
Pro eshell is cross platform
You can use the underlying operating system shell as a terminal emulation in an Emacs buffer. Don't like the default shell for your configuration? You can change it to your liking.
Pro Excellent Lisp editing support
Built-in packages make editing Lisp source code feel natural.
Pro use-package and org-mode
Missing some neural package that predicts actions
Maybe in the next release ...

Pro BitBucket integration
Integrates with BitBucket and allows logging in with your BitBucket account. It's possible to launch Codeanywhere from within BitBucket's repo by adding Codeanywhere integration as an add-on.
Pro Dropbox and Google Drive support
Codeanywhere allows connecting and pulling development files from a Dropbox or a Google Drive account, making it easy to sync development files across devices.

Pro Full terminal access
CodeAnywhere gives users full terminal access.

Pro Unlimited revisions
Each action performed on any file from any resource will be saved forever.

Pro Github integration
Integrates with Github and allows logging in with your Github account.
Pro Has mobile apps for all major mobile OSs
Codeanywhere has apps for iOS, Android, Kindle Fire, Windows, and Blackberry.

Pro SFTP access
Allows connecting code via FTP, SFTP.
Pro Good editor
Supports multiple cursors. Has code completion for JavaScript, PHP, HTML, CSS and linting for JavaScript and CSS.
Pro Allows inviting collaborators with a link
Codeanywhere has a feature called Share Links, that allows users to collaborate with others on their projects in real-time by simply sharing a link to their work.
Pro Multiple devboxes
DevBoxes are saveable, fully customizable development environments that run on either Open VZ or Docker and each has a dedicated amount of memory and disk space. Multiple devboxes can be run at the same time.
Pro SSH Terminal
Even for 3rd party SSH connections.
Pro Integration with DigitalOcean
CodeAnywhere recently partnered up with DigitalOcean. Now users can manage, spin up and provision DigitalOcean droplets all from the CodeAnywhere IDE. This is a great addition for both products, combining the power of an affordable host with the portability and power of CodeAnywhere IDE.
Pro OneDrive integration
Similar to their Dropbox integration, it gives you full access.
Cons
Con Learning curve is long
While it's better than it used to be, with most functions being possible through the menu, Emacs is still quite a bit different from your standard editor. You'll need to learn new keyboard shortcuts.
Con Sometimes the extensibility can distract you from your actual work
If I ever want to lose half a day, I'll start by tweaking my .spacemacs config file.
Con Keyboard combinations can be confusing for new users
For example, for navigation it uses the b, n, p, l keys. Which for some people may seem strange in the begging. However they can be changed easily.
Con Documentation is not beginner-friendly
Although lots of good built-in documentation _exists_, I have after four years of Emacs as my primary editor not figured out how to actually make use of it, and rely completely on Google / StackOverflow for help.
Con Hard customization
For customization, you need to learn Lisp
Con A lot of jokes in this serious software
Con Using Emacs on a new machine without your .emacs file
Con No debugging options found (stepping through code)
Con Non free/libre (proprietary)
Con Web terminal window doesn't always run
In many instances, opening a terminal window in CodeEnvy would continue to load eternally.
Con Customer support is virtually non-existent
Con Custom domains do not work
The custom domain feature fails at the SSL cert, even if you are bringing your own via Cloudflare, etc. Running on port 80 appears to break the site. This is especially frustrating when you paid an extra $24 for 15 custom domains that you cannot use. Support is non-existent so they will not help resolve the issue.
Con Very unstable
It's a nice IDE when it works, but suffers a lot from instability with things like being unable to save files, or not starting up, as well as crashes, etc.
Con Does not jump to definitions
Unable to navigate the class definition or declaration.
Con iOS app hasn't been updated in almost 3 years
Update as of August 20 2017.
Con Unclear which languages are supported
After ploughing through the website searching which languages are supported, no information could be found.

Con Web editor on iPad is severely lacking
Codeanywhere relies on right click for major actions but doesn't support this interaction on iPad. Selecting listed Dev box URLs to access site is also unworkable in practice. iPad app allows the actions but has very limited set of Dev box controls.
Using an external keyboard with the app can also be problematic as the arrow keys don't work.
Con SSH Port will be different each time you start your DevBox
Only for Always on DevBoxes will SSH ports remain static.
Con Does not have a function name list in side panel view
Con Can't use SFTP with GIT
Con UI is not optimized and zoom is applied to the entire screen, rather than just the editor
The buttons are way too small. The UI feels washed out and opaque. Zoom (Ctrl++) is applied on the entire screen and not just on the editor.
Con 2 Factor authentication is a joke
Con Confusing, not user friendly
It's so confusing versus other IDEs. Not recommended for newbies and programming students.
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