vim.wasm: Vim Ported to WebAssembly
- Please access from a desktop browser (Chrome/Firefox/Safari/Edge). Safari seems the best on macOS.
- Please avoid slow networks. Your browser will fetch total of around 1MB files.
- vim.wasm takes key inputs from DOM
keydownevent. Please disable your browser extensions which affect key inputs (incognito mode would be the best).
- This project is very early phase of experiment. Currently only tiny features are supported. More features will be implemented (please see TODO section). And you may notice soon on trying it... it's buggy :)
- If inputting something does not change anything, please try to click somewhere in the page. Vim may have lost the focus.
- You can try vimtutor by
- Vim exits on
:quit, but the command does not close a browser tab. Please close it manually :)
The goal of this project is running Vim editor on browser by compiling Vim C sources into WebAssembly.
How It Works
WebAssembly frontend for Vim is implemented as a new GUI frontend. C sources are
compiled to each LLVM bitcode files and then they are linked to one bitcode file
emcc finally compiles the
The difference I faced at first was the lack of terminal library such as ncurses.
configure script to ignore the terminal library check. It's OK since
GUI frontend for Wasm is always used instead of CUI frontend. I needed many
workarounds to pass
emscripten provides Unix-like environment. So
os_unix.c can support Wasm. However,
some features are not supported by emscripten. I added many
guards to disable features which cannot be supported by Wasm (i.e.
support, PTY support, signal handlers are stubbed, ...etc).
gui_wasm.c heavily referencing
gui_w32.c. Event loop
gui_mch_wait_for_chars()) is simply implemented with
C sources are compiled (with many optimizations) into LLVM bitcode with Clang
which is integrated to emscripten. Then all bitcode files (
.o) are linked to
one bitcode file
llvm-link linker (also integrated to emscripten).
It is created as
wasm/runtime.ts using emscripten API.
It draws Vim screen to
<canvas/> element with rendering events such as
'draw text', 'scroll screen', 'set foreground color', 'clear rect', ...etc.
emcc (emscripten's C compiler) compiles the
vim.html with preloaded Vim runtime files (i.e. colorscheme) using binaryen.
Runtime files are put on a virtual file system provided by emscripten on a browser.
vim.html with a web server and accessing to it with browser opens
Vim. It works.
User interaction is very simple. You input something with keyboard. Browser takes
to Wasm thanks to emscripten's JS to C API. Sent input is added to a buffer in C
layer. It affects the editor's state.
An editor core implemented in C calculates rendering events and sends it to
rendering events and stores them into a queue. On animation frames, it draws
<canvas/> element in the web page.
Finally you can see the rendered results in the page.
Please make sure that Emscripten and binaryen (I'm using 1.38.6) are installed.
If you use macOS, they can be installed with
brew install emscripten binaryen.
You can use
build.sh script to hack this project. Just after cloning this
repository, simply run
./build.sh and it builds vim.wasm in
It takes time and CPU power a lot.
Finally host the
wasm/ directly on
localhost with web server such as
python -m http.server 1234. Accessing to
localhost:1234/vim.html will start
Vim with debug build. Note that it's much slower than release build since many
debug features are enabled.
Please note that this repository's
wasm branch is frequently rebased on the
latest vim/vim master branch. If you want to hack this project, please ensure
to create your own branch and merge
wasm branch into your branch by
sleep(). By default, emscripten compiles
sleep()into a busy loop. So vim.wasm is using Emterpreter which provides
emscripten_sleep(). Some whitelisted functions are run with Emterpreter. But this feature is not so stable. It makes built binaries larger and compilation longer.
some C APIs breaks Emterpreter stack. This also means that calling C functions
stringparameter does not work.
Development is managed in GitHub Projects.
- 'small' (or larger) features support (currently only 'tiny' features are supported)
- Async event loop (to disable Emterpreter)
- Mouse support
- Packaging vim.wasm as npm package or ES Modules as Web Component
- Save files to local on
All additional files in this repository are licensed under the same license as
Vim (VIM LICENSE). Please see
:help license for more detail.
Original README is following.
What is Vim?
Vim is a greatly improved version of the good old UNIX editor Vi. Many new
features have been added: multi-level undo, syntax highlighting, command line
history, on-line help, spell checking, filename completion, block operations,
script language, etc. There is also a Graphical User Interface (GUI)
available. Still, Vi compatibility is maintained, those who have Vi "in the
fingers" will feel at home. See
runtime/doc/vi_diff.txt for differences with
This editor is very useful for editing programs and other plain text files. All commands are given with normal keyboard characters, so those who can type with ten fingers can work very fast. Additionally, function keys can be mapped to commands by the user, and the mouse can be used.
Vim runs under MS-Windows (NT, 2000, XP, Vista, 7, 8, 10), Macintosh, VMS and almost all flavours of UNIX. Porting to other systems should not be very difficult. Older versions of Vim run on MS-DOS, MS-Windows 95/98/Me, Amiga DOS, Atari MiNT, BeOS, RISC OS and OS/2. These are no longer maintained.
You can often use your favorite package manager to install Vim. On Mac and Linux a small version of Vim is pre-installed, you still need to install Vim if you want more features.
There are separate distributions for Unix, PC, Amiga and some other systems.
README.md file comes with the runtime archive. It includes the
documentation, syntax files and other files that are used at runtime. To run
Vim you must get either one of the binary archives or a source archive.
Which one you need depends on the system you want to run it on and whether you
want or must compile it yourself. Check http://www.vim.org/download.php for
an overview of currently available distributions.
Some popular places to get the latest Vim:
- Check out the git repository from github.
- Get the source code as an archive.
- Get a Windows executable from the vim-win32-installer repository.
If you obtained a binary distribution you don't need to compile Vim. If you
obtained a source distribution, all the stuff for compiling Vim is in the
src directory. See
src/INSTALL for instructions.
See one of these files for system-specific instructions. Either in the READMEdir directory (in the repository) or the top directory (if you unpack an archive):
README_ami.txt Amiga README_unix.txt Unix README_dos.txt MS-DOS and MS-Windows README_mac.txt Macintosh README_vms.txt VMS
There are other
README_*.txt files, depending on the distribution you used.
The Vim tutor is a one hour training course for beginners. Often it can be
:help tutor for more information.
The best is to use
:help in Vim. If you don't have an executable yet, read
runtime/doc/help.txt. It contains pointers to the other documentation
files. The User Manual reads like a book and is recommended to learn to use
Vim is Charityware. You can use and copy it as much as you like, but you are
encouraged to make a donation to help orphans in Uganda. Please read the file
runtime/doc/uganda.txt for details (do
:help uganda inside Vim).
Summary of the license: There are no restrictions on using or distributing an unmodified copy of Vim. Parts of Vim may also be distributed, but the license text must always be included. For modified versions a few restrictions apply. The license is GPL compatible, you may compile Vim with GPL libraries and distribute it.
Fixing bugs and adding new features takes a lot of time and effort. To show your appreciation for the work and motivate Bram and others to continue working on Vim please send a donation.
Since Bram is back to a paid job the money will now be used to help children
in Uganda. See
runtime/doc/uganda.txt. But at the same time donations
increase Bram's motivation to keep working on Vim!
For the most recent information about sponsoring look on the Vim web site: http://www.vim.org/sponsor/
If you would like to help making Vim better, see the CONTRIBUTING.md file.
The latest news about Vim can be found on the Vim home page: http://www.vim.org/
If you still have problems or any other questions, use one of the mailing lists to discuss them with Vim users and developers: http://www.vim.org/maillist.php
If nothing else works, report bugs directly: Bram Moolenaar Bram@vim.org
Send any other comments, patches, flowers and suggestions to: Bram Moolenaar Bram@vim.org
README.md for version 8.1 of Vim: Vi IMproved.