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| -rw-r--r-- | CONTRIBUTING.md | 16 |
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diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md index 19f7dcff7..5f7ddbc9c 100644 --- a/CONTRIBUTING.md +++ b/CONTRIBUTING.md @@ -53,6 +53,22 @@ The ESM modules in Bun are located in `src/bun.js/*.exports.js`. Unlike other co The module loader is in `src/bun.js/module_loader.zig`. +### JavaScript Builtins + +JavaScript builtins are located in `src/bun.js/builtins/*.js`. + +These files support a JavaScriptCore-only syntax for internal slots. `@` is used to access an internal slot. For example: `new @Array(123)` will create a new `Array` similar to `new Array(123)`, except if a library modifies the `Array` global, it will not affect the internal slot (`@Array`). These names must be allow-listed in `BunBuiltinNames.h` (though JavaScriptCore allowlists some names by default). + +They can not use or reference ESM-modules. The files that end with `*Internals.js` are automatically loaded globally. Most usage of internals right now are the stream implementations (which share a lot of code from Safari/WebKit) and ImportMetaObject (which is how `require` is implemented in the runtime) + +To regenerate the builtins: + +```sh +make clean-bindings && make generate-builtins && make bindings -j10 +``` + +It is recommended that you have ccache installed or else you will spend a lot of time waiting for the bindings to compile. + ### Memory management in Bun's JavaScript runtime TODO: fill this out (for now, use `JSC.Strong` in most cases) |