703eacbe13
Also adds pretty printing for WeakRef values in the REPL :) |
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.forgejo/workflows | ||
docs | ||
src | ||
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build.zig | ||
build.zig.zon | ||
LICENSE | ||
README.md |
Kiesel
⚡ A JavaScript engine written in Zig
Introduction
Kiesel (/ˈkiːzəl/) is a JavaScript engine written from scratch for the purpose of me learning the Zig programming language, with the eventual goal of full support for the latest ECMAScript standard. It features a custom bytecode VM and runtime, and aims to implement as much as possible in pure Zig - currently with the following exceptions:
- bdwgc for garbage collected allocations
- libregexp for regular expressions
- ICU4X for
Intl
-related functionality
A simple CLI (REPL/file interpreter) is available but being easy to embed in other projects is also a goal.
The implementation style is similar to LibJS - the JS engine used in SerenityOS and the Ladybird browser which I worked on before - in various aspects, most notably the desire to stay very close to spec. Development is still at an early stage and the engine's usefulness thus limited. While there are various things that already work well, there's an equal amount of things that don't :^)
Please refrain from filing issues for missing features - many are missing! Similarly, please get in touch before starting to work on something larger than a bug fix.
Further reading:
- Kiesel Devlog #1: Now passing 25% of test262!
- Kiesel Devlog #2: Iterators, more math, and a bug in the Zig stdlib
- Kiesel Devlog #3: Accessors, Date/Map/Set, test262 history graph
- Kiesel Devlog #4: The biggest update yet!
- Kiesel Devlog #5: Progress powered by the Shadow web engine
- Kiesel Devlog #6: Catching Up :^)
- Kiesel Devlog #7: Happy Birthday!
- Kiesel Devlog #8: SSR, but it's CGI
- Kiesel Devlog #9: JavaScript on a Printer
- Kiesel Devlog #10: Let's Make It Fast!
Build
Dependencies managed through build.zig.zon
will be
installed automatically when building for the first time.
To build and run the Kiesel CLI:
zig build run
NOTE: Kiesel targets the master branch of Zig. This means that the build breaks semi-regularly, which I will usually fix as soon as I notice.
Build Options
These can be set by passing -D<name>=<value>
to zig build
.
Name | Default | Description |
---|---|---|
enable-annex-b |
true |
Enables support for ECMA-262 Annex B language features. |
enable-intl |
true |
Enables support for ECMA-402 (Intl ), which depends on cargo being available for the ICU4X library. |
enable-legacy |
true |
Enables support for legacy language features |
enable-libgc |
true |
Enables building with libgc |
enable-libregexp |
true |
Enables building with libregexp |
enable-nan-boxing |
true on x86_64/aarch64, false otherwise |
Enables NaN-boxing which requires a maximum of 48 bits of addressable memory |
Usage
Usage: kiesel [options] [file]
Options:
-c, --command Run the given code instead of reading from a file
-d, --debug Enable debug mode
--disable-gc Disable garbage collection
-m, --module Run code as a module instead of a script
--print-ast Print the parsed AST
--print-bytecode Print the generated bytecode
--print-gc-warnings Print GC warnings, e.g. OOM
--print-promise-rejection-warnings Print promise rejection warnings
-p, --print-result Print the evaluated result
-v, --version Print version information and exit
-h, --help Print help text and exit