\n\n[](https://github.com/toyobayashi/emnapi/actions/workflows/main.yml)\n\n[Node-API](https://nodejs.org/docs/latest/api/n-api.html) implementation for [Emscripten](https://emscripten.org/index.html), [wasi-sdk](https://github.com/WebAssembly/wasi-sdk) and clang with wasm support.\n\nThis project aims to\n\n- Help users port their or existing Node-API native addons to wasm with code change as less as possible.\n- Make runtime behavior matches native Node.js as much as possible.\n\nThis project also powers the WebAssembly feature for [napi-rs](https://github.com/napi-rs/napi-rs), and enables many Node.js native addons to run on [StackBlitz](https://stackblitz.com)'s WebContainer.\n\n[Node-API changes](https://github.com/nodejs/node/pulls?q=is%3Apr+label%3Anode-api+) will be synchronized into this repo.\n\nSee documentation for more details:\n- [https://toyobayashi.github.io/emnapi-docs/guide/](https://toyobayashi.github.io/emnapi-docs/guide/)\n- [https://emnapi-docs.vercel.app/guide/](https://emnapi-docs.vercel.app/guide/)\n\n中文文档：\n- [https://toyobayashi.github.io/emnapi-docs/zh/guide/](https://toyobayashi.github.io/emnapi-docs/zh/guide/)\n- [https://emnapi-docs.vercel.app/zh/guide/](https://emnapi-docs.vercel.app/zh/guide/)\n\n[Full API List](https://toyobayashi.github.io/emnapi-docs/reference/list.html)\n\n[How to build Node-API official examples](https://github.com/toyobayashi/node-addon-examples)\n\nIf you want to deep dive into WebAssembly, highly recommend you to visit [learn-wasm.dev](https://learn-wasm.dev?via=toyobayashi).\n\n## Prerequests\n\nYou will need to install:\n\n- Node.js `>= v16.15.0`\n- npm `>= v8`\n- Emscripten `>= v3.1.9` / wasi-sdk / LLVM clang with wasm support\n- (Optional) CMake `>= v3.13`\n- (Optional) node-gyp `>= v10.2.0`\n- (Optional) ninja\n- (Optional) make\n- (Optional) [node-addon-api](https://github.com/nodejs/node-addon-api) `>= 6.1.0`\n\nThere are several choices to get `make` for Windows user\n\n- Install [mingw-w64](https://www.mingw-w64.org/downloads/), then use `mingw32-make`\n- Download [MSVC prebuilt binary of GNU make](https://github.com/toyobayashi/make-win-build/releases), add to `%Path%` then rename it to `mingw32-make`\n- Install [Visual Studio 2022](https://visualstudio.microsoft.com/) C++ desktop workload, use `nmake` in `Visual Studio Developer Command Prompt`\n- Install [Visual C++ Build Tools](https://visualstudio.microsoft.com/visual-cpp-build-tools/), use `nmake` in `Visual Studio Developer Command Prompt`\n\nVerify your environment:\n\n```bash\nnode -v\nnpm -v\nemcc -v\n\n# clang -v\n# clang -print-targets # ensure wasm32 target exists\n\ncmake --version\n\n# if you use node-gyp\nnode-gyp --version\n\n# if you use ninja\nninja --version\n\n# if you use make\nmake -v\n\n# if you use nmake in Visual Studio Developer Command Prompt\nnmake /?\n```\n\n## Build from source\n\nYou need to set `EMSDK` and `WASI_SDK_PATH` environment variables.\n\n```bash\ngit clone https://github.com/toyobayashi/emnapi.git\ncd ./emnapi\nnpm install -g node-gyp\nnpm install\nnpm run build # output ./packages/*/dist\nnode ./script/release.js # output ./out\n\n# test\nnpm run rebuild:test\nnpm test\n```\n\nSee [CONTRIBUTING](https://github.com/toyobayashi/emnapi/blob/main/CONTRIBUTING.md) for more details.\n\n## Quick Start\n\n### NPM Install\n\n```bash\nnpm install -D emnapi\nnpm install @emnapi/runtime\n\n# for non-emscripten\nnpm install @emnapi/core\n\n# if you use node-addon-api\nnpm install node-addon-api\n```\n\nEach package should match the same version.\n\n### Using C\n\nCreate `hello.c`.\n\n```c\n#include \n\n#define NODE_API_CALL(env, the_call) \\\n do { \\\n if ((the_call) != napi_ok) { \\\n const napi_extended_error_info *error_info; \\\n napi_get_last_error_info((env), &error_info); \\\n bool is_pending; \\\n const char* err_message = error_info->error_message; \\\n napi_is_exception_pending((env), &is_pending); \\\n if (!is_pending) { \\\n const char* error_message = err_message != NULL ? \\\n err_message : \\\n \"empty error message\"; \\\n napi_throw_error((env), NULL, error_message); \\\n } \\\n return NULL; \\\n } \\\n } while (0)\n\nstatic napi_value js_hello(napi_env env, napi_callback_info info) {\n napi_value world;\n const char* str = \"world\";\n NODE_API_CALL(env, napi_create_string_utf8(env, str, NAPI_AUTO_LENGTH, &world));\n return world;\n}\n\nNAPI_MODULE_INIT() {\n napi_value hello;\n NODE_API_CALL(env, napi_create_function(env, \"hello\", NAPI_AUTO_LENGTH,\n js_hello, NULL, &hello));\n NODE_API_CALL(env, napi_set_named_property(env, exports, \"hello\", hello));\n return exports;\n}\n```\n\nThe C code is equivalant to the following JavaScript:\n\n```js\nmodule.exports = (function (exports) {\n const hello = function hello () {\n // native code in js_hello\n const world = 'world'\n return world\n }\n\n exports.hello = hello\n return exports\n})(module.exports)\n```\n\n#### Building\n\n\nemscripten \n\n```bash\nemcc -O3 \\\n -DBUILDING_NODE_EXTENSION \\\n \"-DNAPI_EXTERN=__attribute__((__import_module__(\\\"env\\\")))\" \\\n -I./node_modules/emnapi/include/node \\\n -L./node_modules/emnapi/lib/wasm32-emscripten \\\n --js-library=./node_modules/emnapi/dist/library_napi.js \\\n -sEXPORTED_FUNCTIONS=\"['_malloc','_free','_napi_register_wasm_v1','_node_api_module_get_api_version_v1']\" \\\n -sEXPORTED_RUNTIME_METHODS=['emnapiInit'] \\\n -o hello.js \\\n hello.c \\\n -lemnapi\n```\n\n\n\n\nwasi-sdk \n\n```bash\nclang -O3 \\\n -DBUILDING_NODE_EXTENSION \\\n -I./node_modules/emnapi/include/node \\\n -L./node_modules/emnapi/lib/wasm32-wasi \\\n --target=wasm32-wasi \\\n --sysroot=$WASI_SDK_PATH/share/wasi-sysroot \\\n -mexec-model=reactor \\\n -Wl,--initial-memory=16777216 \\\n -Wl,--export-dynamic \\\n -Wl,--export=malloc \\\n -Wl,--export=free \\\n -Wl,--export=napi_register_wasm_v1 \\\n -Wl,--export-if-defined=node_api_module_get_api_version_v1 \\\n -Wl,--import-undefined \\\n -Wl,--export-table \\\n -o hello.wasm \\\n hello.c \\\n -lemnapi\n```\n\n\n\n\nclang wasm32 \n\nChoose `libdlmalloc.a` or `libemmalloc.a` for `malloc` and `free`.\n\n```bash\nclang -O3 \\\n -DBUILDING_NODE_EXTENSION \\\n -I./node_modules/emnapi/include/node \\\n -L./node_modules/emnapi/lib/wasm32 \\\n --target=wasm32 \\\n -nostdlib \\\n -Wl,--no-entry \\\n -Wl,--initial-memory=16777216 \\\n -Wl,--export-dynamic \\\n -Wl,--export=malloc \\\n -Wl,--export=free \\\n -Wl,--export=napi_register_wasm_v1 \\\n -Wl,--export-if-defined=node_api_module_get_api_version_v1 \\\n -Wl,--import-undefined \\\n -Wl,--export-table \\\n -o hello.wasm \\\n hello.c \\\n -lemnapi \\\n -ldlmalloc # -lemmalloc\n```\n\n\n\n#### Initialization\n\nTo initialize emnapi, you need to import the emnapi runtime to create a `Context` by `createContext` or `getDefaultContext` first.\nEach context owns isolated Node-API object such as `napi_env`, `napi_value`, `napi_ref`. If you have multiple emnapi modules, you should reuse the same `Context` across them. \n\n```ts\ndeclare namespace emnapi {\n // module '@emnapi/runtime'\n export class Context { /* ... */ }\n /** Create a new context */\n export function createContext (): Context\n /** Create or get */\n export function getDefaultContext (): Context\n // ...\n}\n```\n\n\nemscripten \n\nthen call `Module.emnapiInit` after emscripten runtime initialized.\n`Module.emnapiInit` only do initialization once, it will always return the same binding exports after successfully initialized.\n\n```ts\ndeclare namespace Module {\n interface EmnapiInitOptions {\n context: emnapi.Context\n\n /** node_api_get_module_file_name */\n filename?: string\n\n /**\n * Support following async_hooks related things\n * on Node.js runtime only\n * \n * napi_async_init,\n * napi_async_destroy,\n * napi_make_callback,\n * async resource parameter of\n * napi_create_async_work and napi_create_threadsafe_function\n */\n nodeBinding?: typeof import('@emnapi/node-binding')\n\n /** See Multithread part */\n asyncWorkPoolSize?: number\n }\n export function emnapiInit (options: EmnapiInitOptions): any\n}\n```\n\n```html\n\n\n\n```\n\nIf you are using `Visual Studio Code` and have `Live Server` extension installed, you can right click the HTML file in Visual Studio Code source tree and click `Open With Live Server`, then you can see the hello world alert!\n\nRunning on Node.js:\n\n```js\nconst emnapi = require('@emnapi/runtime')\nconst Module = require('./hello.js')\n\nModule.onRuntimeInitialized = function () {\n let binding\n try {\n binding = Module.emnapiInit({ context: emnapi.getDefaultContext() })\n } catch (err) {\n console.error(err)\n return\n }\n const msg = `hello ${binding.hello()}`\n console.log(msg)\n}\n\n// if -sMODULARIZE=1\nModule({ /* Emscripten module init options */ }).then((Module) => {\n const binding = Module.emnapiInit({ context: emnapi.getDefaultContext() })\n})\n```\n\n\n\n\nwasi-sdk or clang wasm32 \n\nFor non-emscripten, you need to use `@emnapi/core`. The initialization is similar to emscripten.\n\n```html\n\n\n\n```\n\nUsing WASI on Node.js\n\n```js\nconst { instantiateNapiModule } = require('@emnapi/core')\nconst { getDefaultContext } = require('@emnapi/runtime')\nconst { WASI } = require('wasi')\nconst fs = require('fs')\n\ninstantiateNapiModule(fs.promises.readFile('./hello.wasm'), {\n wasi: new WASI({ /* ... */ }),\n context: getDefaultContext(),\n overwriteImports (importObject) {\n // importObject.env = {\n // ...importObject.env,\n // ...importObject.napi,\n // ...importObject.emnapi,\n // // ...\n // }\n }\n}).then(({ instance, module, napiModule }) => {\n const binding = napiModule.exports\n // ...\n})\n```\n\nUsing WASI on browser, you can use WASI polyfill in [wasm-util](https://github.com/toyobayashi/wasm-util),\nand [memfs-browser](https://github.com/toyobayashi/memfs-browser)\n\n```js\nimport { instantiateNapiModule } from '@emnapi/core'\nimport { getDefaultContext } from '@emnapi/runtime'\nimport { WASI } from '@tybys/wasm-util'\nimport { Volume, createFsFromVolume } from 'memfs-browser'\n\nconst fs = createFsFromVolume(Volume.fromJSON({ /* ... */ }))\ninstantiateNapiModule(fetch('./hello.wasm'), {\n wasi: new WASI({ fs, /* ... */ })\n context: getDefaultContext(),\n overwriteImports (importObject) {\n // importObject.env = {\n // ...importObject.env,\n // ...importObject.napi,\n // ...importObject.emnapi,\n // // ...\n // }\n }\n}).then(({ instance, module, napiModule }) => {\n const binding = napiModule.exports\n // ...\n})\n```\n\n\n\n### Using C++ and node-addon-api\n\nRequire [`node-addon-api`](https://github.com/nodejs/node-addon-api) `>= 6.1.0`\n\n```bash\nnpm install node-addon-api\n```\n\n**Note: C++ wrapper can only be used to target Node.js v14.6.0+ and modern browsers those support `FinalizationRegistry` and `WeakRef` ([v8 engine v8.4+](https://v8.dev/blog/v8-release-84))!**\n\nCreate `hello.cpp`.\n\n```cpp\n#include \n\nNapi::String Method(const Napi::CallbackInfo& info) {\n Napi::Env env = info.Env();\n return Napi::String::New(env, \"world\");\n}\n\nNapi::Object Init(Napi::Env env, Napi::Object exports) {\n exports.Set(Napi::String::New(env, \"hello\"),\n Napi::Function::New(env, Method)).Check();\n return exports;\n}\n\nNODE_API_MODULE(NODE_GYP_MODULE_NAME, Init)\n```\n\nCompile `hello.cpp` using `em++`. C++ exception is disabled by Emscripten default, and not supported by wasi-sdk, so predefine `-DNAPI_DISABLE_CPP_EXCEPTIONS` and `-DNODE_ADDON_API_ENABLE_MAYBE` here. If you would like to enable C++ exception, use `-sDISABLE_EXCEPTION_CATCHING=0` instead and remove `.Check()` call. See official documentation [here](https://github.com/nodejs/node-addon-api/blob/main/doc/error_handling.md).\n\n#### Building\n\n\nemscripten \n\n```bash\nem++ -O3 \\\n -DBUILDING_NODE_EXTENSION \\\n \"-DNAPI_EXTERN=__attribute__((__import_module__(\\\"env\\\")))\" \\\n -DNAPI_DISABLE_CPP_EXCEPTIONS \\\n -DNODE_ADDON_API_ENABLE_MAYBE \\\n -I./node_modules/emnapi/include/node \\\n -I./node_modules/node-addon-api \\\n -L./node_modules/emnapi/lib/wasm32-emscripten \\\n --js-library=./node_modules/emnapi/dist/library_napi.js \\\n -sEXPORTED_FUNCTIONS=\"['_malloc','_free','_napi_register_wasm_v1','_node_api_module_get_api_version_v1']\" \\\n -sEXPORTED_RUNTIME_METHODS=['emnapiInit'] \\\n -o hello.js \\\n hello.cpp \\\n -lemnapi\n```\n\n\n\n\nwasi-sdk \n\n```bash\nclang++ -O3 \\\n -DBUILDING_NODE_EXTENSION \\\n -DNAPI_DISABLE_CPP_EXCEPTIONS \\\n -DNODE_ADDON_API_ENABLE_MAYBE \\\n -I./node_modules/emnapi/include/node \\\n -I./node_modules/node-addon-api \\\n -L./node_modules/emnapi/lib/wasm32-wasi \\\n --target=wasm32-wasi \\\n --sysroot=$WASI_SDK_PATH/share/wasi-sysroot \\\n -fno-exceptions \\\n -mexec-model=reactor \\\n -Wl,--initial-memory=16777216 \\\n -Wl,--export-dynamic \\\n -Wl,--export=malloc \\\n -Wl,--export=free \\\n -Wl,--export=napi_register_wasm_v1 \\\n -Wl,--export-if-defined=node_api_module_get_api_version_v1 \\\n -Wl,--import-undefined \\\n -Wl,--export-table \\\n -o hello.wasm \\\n hello.cpp \\\n -lemnapi\n```\n\n\n\n\nclang wasm32 \n\n`node-addon-api` is using the C++ standard libraries, so you must use WASI if you are using `node-addon-api`.\n\nYou can still use `wasm32-unknown-unknown` target if you use Node-API C API only in C++.\n\n```bash\nclang++ -O3 \\\n -DBUILDING_NODE_EXTENSION \\\n -I./node_modules/emnapi/include/node \\\n -L./node_modules/emnapi/lib/wasm32 \\\n --target=wasm32 \\\n -fno-exceptions \\\n -nostdlib \\\n -Wl,--no-entry \\\n -Wl,--initial-memory=16777216 \\\n -Wl,--export-dynamic \\\n -Wl,--export=malloc \\\n -Wl,--export=free \\\n -Wl,--export=napi_register_wasm_v1 \\\n -Wl,--export-if-defined=node_api_module_get_api_version_v1 \\\n -Wl,--import-undefined \\\n -Wl,--export-table \\\n -o node_api_c_api_only.wasm \\\n node_api_c_api_only.cpp \\\n -lemnapi \\\n -ldlmalloc # -lemmalloc\n```\n\n`operator new` and `operator delete`.\n\n```cpp\n#include \n\nextern \"C\" void* malloc(size_t size);\nextern \"C\" void free(void* p);\n\nvoid* operator new(size_t size) {\n return malloc(size);\n}\n\nvoid operator delete(void* p) noexcept {\n free(p);\n}\n\nvoid operator delete(void* p, size_t) noexcept {\n free(p);\n}\n```\n\n\n\n### Using CMake\n\nCreate `CMakeLists.txt`.\n\n```cmake\ncmake_minimum_required(VERSION 3.13)\n\nproject(emnapiexample)\n\nadd_subdirectory(\"${CMAKE_CURRENT_SOURCE_DIR}/node_modules/emnapi\")\n\nadd_executable(hello hello.c)\n\ntarget_link_libraries(hello emnapi)\nif(CMAKE_SYSTEM_NAME STREQUAL \"Emscripten\")\n target_link_options(hello PRIVATE\n \"-sEXPORTED_FUNCTIONS=['_malloc','_free','_napi_register_wasm_v1','_node_api_module_get_api_version_v1']\"\n \"-sEXPORTED_RUNTIME_METHODS=['emnapiInit']\"\n )\nelseif(CMAKE_SYSTEM_NAME STREQUAL \"WASI\")\n set_target_properties(hello PROPERTIES SUFFIX \".wasm\")\n target_link_options(hello PRIVATE\n \"-mexec-model=reactor\"\n \"-Wl,--export=napi_register_wasm_v1\"\n \"-Wl,--export-if-defined=node_api_module_get_api_version_v1\"\n \"-Wl,--initial-memory=16777216,--export-dynamic,--export=malloc,--export=free,--import-undefined,--export-table\"\n )\nelseif((CMAKE_C_COMPILER_TARGET STREQUAL \"wasm32\") OR (CMAKE_C_COMPILER_TARGET STREQUAL \"wasm32-unknown-unknown\"))\n set_target_properties(hello PROPERTIES SUFFIX \".wasm\")\n target_link_options(hello PRIVATE\n \"-nostdlib\"\n \"-Wl,--export=napi_register_wasm_v1\"\n \"-Wl,--export-if-defined=node_api_module_get_api_version_v1\"\n \"-Wl,--no-entry\"\n \"-Wl,--initial-memory=16777216,--export-dynamic,--export=malloc,--export=free,--import-undefined,--export-table\"\n )\n target_link_libraries(hello dlmalloc)\n # target_link_libraries(hello emmalloc)\nendif()\n```\n\nIf you use node-addon-api, you can use `-DEMNAPI_FIND_NODE_ADDON_API=ON` or manually add node-addon-api directory to the include dir via `include_directories()` or `target_include_directories()`.\n\n```bash\nmkdir build\n\n# emscripten\nemcmake cmake -DCMAKE_BUILD_TYPE=Release \\\n -DEMNAPI_FIND_NODE_ADDON_API=ON \\\n -G Ninja -H. -Bbuild\n\n# wasi-sdk\ncmake -DCMAKE_TOOLCHAIN_FILE=$WASI_SDK_PATH/share/cmake/wasi-sdk.cmake \\\n -DWASI_SDK_PREFIX=$WASI_SDK_PATH \\\n -DEMNAPI_FIND_NODE_ADDON_API=ON \\\n -DCMAKE_BUILD_TYPE=Release \\\n -G Ninja -H. -Bbuild\n\n# wasm32\ncmake -DCMAKE_TOOLCHAIN_FILE=node_modules/emnapi/cmake/wasm32.cmake \\\n -DLLVM_PREFIX=$WASI_SDK_PATH \\\n -DCMAKE_BUILD_TYPE=Release \\\n -G Ninja -H. -Bbuild\n\ncmake --build build\n```\n\nOutput code can run in recent version modern browsers and Node.js latest LTS. IE is not supported.\n\n### Using node-gyp (Experimental)\n\nRequire node-gyp `>= 10.2.0`\n\nSee [emnapi-node-gyp-test](https://github.com/toyobayashi/emnapi-node-gyp-test) for examples.\n\n- Variables\n\nArch: `node-gyp configure --arch=`\n\n```ts\n// node-gyp configure -- -Dvariable_name=value\n\ndeclare var OS: 'emscripten' | 'wasi' | 'unknown' | 'wasm' | ''\n\n/**\n * Enable async work and threadsafe-functions\n * @default 0\n */\ndeclare var wasm_threads: 0 | 1\n\n/** @default 1048576 */\ndeclare var stack_size: number\n\n/** @default 16777216 */\ndeclare var initial_memory: number\n\n/** @default 2147483648 */\ndeclare var max_memory: number\n\n/** @default path.join(path.dirname(commonGypiPath,'./dist/library_napi.js')) */\ndeclare var emnapi_js_library: string\n\n/** @default 0 */\ndeclare var emnapi_manual_linking: 0 | 1\n```\n\n- Create `binding.gyp`\n\n\n```py\n{\n \"targets\": [\n {\n \"target_name\": \"hello\",\n \"sources\": [\n \"hello.c\"\n ],\n \"conditions\": [\n [\"OS == 'emscripten'\", {\n \"product_extension\": \"js\", # required\n\n \"cflags\": [],\n \"cflags_c\": [],\n \"cflags_cc\": [],\n \"ldflags\": []\n }],\n [\"OS == 'wasi'\", {\n # ...\n }],\n [\"OS in ' wasm unknown'\", {\n # ...\n }]\n ]\n }\n ]\n}\n```\n\n- Add the following environment variables.\n\n```bash\n# Linux or macOS\nexport GYP_CROSSCOMPILE=1\n\n# emscripten\nexport AR_target=\"$EMSDK/upstream/emscripten/emar\"\nexport CC_target=\"$EMSDK/upstream/emscripten/emcc\"\nexport CXX_target=\"$EMSDK/upstream/emscripten/em++\"\n\n# wasi-sdk\nexport AR_target=\"$WASI_SDK_PATH/bin/ar\"\nexport CC_target=\"$WASI_SDK_PATH/bin/clang\"\nexport CXX_target=\"$WASI_SDK_PATH/bin/clang++\"\n```\n\n```bat\n@REM Windows\n\nset GYP_CROSSCOMPILE=1\n\n@REM emscripten\ncall set AR_target=%%EMSDK:\\=/%%/upstream/emscripten/emar.bat\ncall set CC_target=%%EMSDK:\\=/%%/upstream/emscripten/emcc.bat\ncall set CXX_target=%%EMSDK:\\=/%%/upstream/emscripten/em++.bat\n\n@REM wasi-sdk\ncall set AR_target=%%WASI_SDK_PATH:\\=/%%/bin/ar.exe\ncall set CC_target=%%WASI_SDK_PATH:\\=/%%/bin/clang.exe\ncall set CXX_target=%%WASI_SDK_PATH:\\=/%%/bin/clang++.exe\n```\n\n- Build\n\n```bash\n# Linux or macOS\n\n# emscripten\nemmake node-gyp rebuild \\\n --arch=wasm32 \\\n --nodedir=./node_modules/emnapi \\\n -- -f make-emscripten # -Dwasm_threads=1\n\n# wasi\nnode-gyp rebuild \\\n --arch=wasm32 \\\n --nodedir=./node_modules/emnapi \\\n -- -f make-wasi # -Dwasm_threads=1\n\n# bare wasm32\nnode-gyp rebuild \\\n --arch=wasm32 \\\n --nodedir=./node_modules/emnapi \\\n -- -f make-wasm # -Dwasm_threads=1\n```\n\n```bat\n@REM Use make generator on Windows\n@REM Run the bat file in POSIX-like environment (e.g. Cygwin)\n\n@REM emscripten\ncall npx.cmd node-gyp configure --arch=wasm32 --nodedir=./node_modules/emnapi -- -f make-emscripten\ncall emmake.bat make -C %~dp0build\n\n@REM wasi\ncall npx.cmd node-gyp configure --arch=wasm32 --nodedir=./node_modules/emnapi -- -f make-wasi\nmake -C %~dp0build\n\n@REM bare wasm32\ncall npx.cmd node-gyp configure --arch=wasm32 --nodedir=./node_modules/emnapi -- -f make-wasm\nmake -C %~dp0build\n```\n\n### Using Rust\n\nSee [napi-rs](https://github.com/napi-rs/napi-rs) \n\n### Multithread\n\nRelated API:\n\n- [napi_*_async_work](https://nodejs.org/dist/latest/docs/api/n-api.html#napi_create_async_work)\n- [napi_*_threadsafe_function](https://nodejs.org/dist/latest/docs/api/n-api.html#asynchronous-thread-safe-function-calls)\n\nThey are available in emnapi, but you need to know more details before you start to use them.\nNow emnapi has 3 implementations of async work and 2 implementations of TSFN:\n\n- Async work\n - A. Libuv threadpool and pthread based implementation in C\n - B. Single thread mock in JavaScript\n - C. Web worker based implementation in C (stack allocation) and JavaScript\n- TSFN\n - D. Libuv and pthread based implementation in C\n - E. Web worker based implementation in JavaScript\n\n| | Library to Link | `wasm32-emscripten` | `wasm32` | `wasm32-wasi` | `wasm32-wasi-threads` |\n|---|------------------------|---------------------|----------|---------------|-----------------------|\n| A | libemnapi-mt.a | ✅ | ❌ | ❌ | ✅ |\n| B | libemnapi-basic(-mt).a | ✅ | ✅ | ✅ | ✅ |\n| C | libemnapi-basic-mt.a | ❌ | ✅ | ❌ | ✅ |\n| D | libemnapi-mt.a | ✅ | ❌ | ❌ | ✅ |\n| E | libemnapi-basic(-mt).a | ✅ | ✅ | ✅ | ✅ |\n\nThere are some limitations on browser about wasi-libc's pthread implementation, for example\n`pthread_mutex_lock` may call `__builtin_wasm_memory_atomic_wait32`(`memory.atomic.wait32`)\nwhich is disallowed in browser JS main thread. While Emscripten's pthread implementation\nhas considered usage in browser. This issue can be solved by upgrading `wasi-sdk` to v26+\nand emnapi v1.5.0+ then pass `--export=emnapi_thread_crashed` to the linker. If you need to\nrun your addon with multithreaded features, we recommend you use A & D or C & E.\n\nNote: For browsers, all the multithreaded features relying on Web Workers (Emscripten pthread also relying on Web Workers)\nrequire cross-origin isolation to enable `SharedArrayBuffer`. You can make a page cross-origin isolated\nby serving the page with these headers:\n\n```\nCross-Origin-Embedder-Policy: require-corp\nCross-Origin-Opener-Policy: same-origin\n```\n\nIf you would like to avoid `SharedArrayBuffer` and cross-origin isolation, please use B & E (link against `libemnapi-basic.a`), see the following table for more details.\n\n#### About Prebuilt Libraries\n\nPrebuilt libraries can be found in the `lib` directory in `emnapi` npm package.\n\n| Library | Description | `wasm32-emscripten` | `wasm32` | `wasm32-wasi` | `wasm32-wasi-threads` |\n|----------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------|----------|---------------|-----------------------------------------|\n| libemnapi.a | no atomics feature.
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