Use cmake + emsdk to build multiple wasm in one time.

Prepare: emscripten 3.1.30

modify emcc.py: https://github.com/Keillion/emscripten/commit/fc55d8790a55fe3b8976a542e1bde47a5295d103

Dynamic link sideModule.

Use webidl.

Generate idl cpp and js for reference

$ /emsdk/upstream/emscripten/tools/webidl_binder mainModule.idl mainModuleGlue

$ mkdir build
$ cd build
$ emcmake cmake ../
$ emmake make

In order to see which system libs are actually needed. refer

$ emmake make VERBOSE=1

html need to be host in an HTTP server. The mimetype of .wasm needs to set as application/wasm.

Not freeing char * return value in webidl will cause a memory leak.

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Most fileds in wasmImport or wasmExport are not needed, I save a slimmed std.js here for reference.