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WASM

When you've written a new code module in a language like C/C++, you can compile it into WebAssembly using a tool like Emscripten.

Get the Emscripten SDK, using these instructions: https://emscripten.org/docs/getting_started/downloads.html

每次用终端窗口，先到 emsdk 目录执行：

# Activate PATH and other environment variables in the current terminal
source ./emsdk_env.sh

Compiling a New C/C++ Module to WebAssembly - WebAssembly | MDN

emcc hello.c -o hello.html 编译后得到：hello.wasm, hello.js, hello.html

直接打开本地文件 HTML 无法使用，原因是：

  • Some browsers (including Chrome) will not run async requests (fetching data from remote server) if you just run the example from a local file. This is because of security restrictions.
  • Server-side languages (such as PHP or Python) require a special server to interpret the code and deliver the results.
  • Browsers commonly treat requests to load resources using the file:// schema as cross-origin requests. So if you load a local file that includes other local files, this may trigger a CORS error.

使用本地服务器后可以正常运行 Demo。

看了它们的 HTML 代码，没有要紧的，核心胶水代码都在 hello.js 里面，可以使用 emcc -o hello2.js hello2.c -O3 仅生成 js 文件，不产生 html。

Emscripten requires a large variety of JavaScript "glue" code to handle memory allocation, memory leaks, and a host of other problems.

If you have a function defined in your C code that you want to call as needed from JavaScript, you can do this using the Emscripten ccall() function.