1 Checkout and build the emscripten_sdk following the instructions here: 2 http://webassembly.org/getting-started/developers-guide/ 3 4 Then, run 5 infra/bots/assets/emscripten_sdk/create_and_upload.py -s /path/to/dir/emsdk 6 7 It will take a while because the emsdk dir is > 26GB.