WASM instructions for Linux are below. Building for wasm is a little tricky, you may be able to get by using the taskcluster artifacts that run on each PR. Each PR runs a build-wasm/opt job. From GitHub actions view, you can "View task in Taskcluster", then under Artifacts, click on public/build/index.html.

If that doesn't work for you, first follow all pre-requisites listed in Linux.md.

Ninja build tool

sudo apt install ninja-build

Install emscripten. The version of emscripten required will depend of the Qt version being used. Check out Qt docs to figure out the required version for your environment.

Make the build directory

mkdir build

Configure using qt-cmake which is in your installer directory

<path to installed Qt>/6.2.4/wasm_32/bin/qt-cmake -S . -B build

Compile

cmake --build build -j$(nproc)

Run the WASM build for development with

npm run wasm:dev

Note: This assumes the final WASM build folder to be /build/wasm_build. If the build folder is different from that, set the WASM_BUILD_DIRECTORY to the chosen build folder.