This is a full self contained working example of the grcpweb-echo example from grpc.io It is not dependend on a big proxy which needs docker, but only uses the simple executable which is part of this repo
It even includes the correct/older version of protoc to compile javascript AND the grcp-web plugin, so no anger and worries...
npm install
npm run postinstall
npm run make
it will compile the proto file and compile the javascript files to be able to run in the browser If already compiled the proto you can also just use npm run build_client for webpacking the javascript for the browser.
npm start
this starts the grpc backend server and the proxy which will forward grpc-calls from localhost:8080 to the backend server at localhost:9090 and vice-versa- Run the client by opening the echotest.html in the browser.