wasm and asm.js releases are available here. The wasm build is what cimbar.org uses. cimbar_js.html can be downloaded and opened/run in a local web browser -- no install required.
To build, use the package-wasm.sh script in a docker container:
docker run --mount type=bind,source="$(pwd)",target="/usr/src/app" -it emscripten/emsdk:3.1.39
Then, inside the container:
bash /usr/src/app/package-wasm.sh
Alternatively, if you have a local emscripten setup, you can try to run the package-wasm.sh commands piecemeal:
To build opencv.js:
cd /path/to/opencv
mkdir opencv-build-wasm
cd opencv-build-wasm
python3 ../platforms/js/build_js.py build_wasm --build_wasm --emscripten_dir=/path/to/emscripten
With opencv.js built:
mkdir build-wasm
cd build-wasm
source /path/to/emscripten/emsdk/emsdk_env.sh
emcmake cmake .. -DUSE_WASM=1 -DOPENCV_DIR=/path/to/opencv
make -j5 install
(do -DUSE_WASM=2 to use asm.js instead of wasm)
Some day!