grpc-tools: add grpc_js param to grpc_out

[badsyntax]

This is a minor change to use the pure JavaScript gRPC Client @grpc/grpc-js instead of the (now deprecated) grpc node package when generating javascript files using the proto compiler. This change is very similar to the generate_package_definition param.

Reasoning:

I understand that it's recommended to use @grpc/proto-loader to the load protos files.

I have some hesitation to adopt this approach, as when using TypeScript, I have to typecast using type assertions to type the grpc client as a ServiceClientConstructor, for example:

const echoService = loadProtoFile(protoFile)
      .EchoService as ServiceClientConstructor;

My client is then defined as:

grpc-node/packages/grpc-js/src/make-client.ts

Lines 83 to 85 in 4ec023c

	export interface ServiceClient extends Client {
	[methodName: string]: Function;
	}

..and I loose all the benefits of (for example) IntelliSense in my IDE. I also don't know if my method calls are correct until I compile the TypeScript to JS. It's not a great developer experience.

The change i'm proposing is to support "grpc_js" within the proto compiler. This will allow me to generate static javascript files that require @grpc/grpc-js instead of grpc, and will allow existing tools to then generate types from those files.

I also feel this a good change to support existing projects & tooling that would like to switch over to using @grpc/grpc-js. It will allow for better adoption as the required changes in the consuming projects are minimal.

[laike9m]

Hi Richard, you mentioned

This will allow me to generate static javascript files that require @grpc/grpc-js instead of grpc, and will allow existing tools to then generate types from those files.

May I ask what tools you're using to generate TS types? I tried grpc_tools_node_protoc_ts but it does not seem to support grpc-js. Thanks.

[laike9m]

Never mind. I saw your PR: improbable-eng/ts-protoc-gen#236

Hope it gets merged soon.

[badsyntax]

@laike9m i'm not sure if the authors of that package are keen to improve it as i've had zero feedback.

i've been meaning to have a look at the new typescript generator offered by @murgatroid99, and i would suggest to consider using that package instead.

see: #528 (comment)

example of how it can be used:

grpc-node/packages/grpc-js/generateTypes.sh

Lines 18 to 20 in 095a3b4

	./node_modules/.bin/proto-loader-gen-types --keepCase --longs String --enums String --defaults --oneofs --json\
	--includeDirs deps/envoy-api/ deps/udpa/ node_modules/protobufjs/ deps/googleapis/ deps/protoc-gen-validate/ \
	-O src/generated/ --grpcLib ../index envoy/service/discovery/v2/ads.proto envoy/api/v2/listener.proto envoy/api/v2/route.proto envoy/api/v2/cluster.proto envoy/api/v2/endpoint.proto

[laike9m]

Great, let me try that out. Thanks for the pointer.

[laike9m]

@laike9m i'm not sure if the authors of that package are keen to improve it as i've had zero feedback.

i've been meaning to have a look at the new typescript generator offered by @murgatroid99, and i would suggest to consider using that package instead.

see: #528 (comment)

example of how it can be used:

grpc-node/packages/grpc-js/generateTypes.sh

Lines 18 to 20 in 095a3b4

	./node_modules/.bin/proto-loader-gen-types --keepCase --longs String --enums String --defaults --oneofs --json\
	--includeDirs deps/envoy-api/ deps/udpa/ node_modules/protobufjs/ deps/googleapis/ deps/protoc-gen-validate/ \
	-O src/generated/ --grpcLib ../index envoy/service/discovery/v2/ads.proto envoy/api/v2/listener.proto envoy/api/v2/route.proto envoy/api/v2/cluster.proto envoy/api/v2/endpoint.proto

I gave it a try, but somehow it confused me. Not sure if I'm doing anything wrong:
#528 (comment)