lnd.xprv/docs/grpc/javascript.md

How to write a simple lnd client in Javascript using node.js

First, you'll need to initialize a simple nodejs project:

npm init (or npm init -f if you want to use the default values without prompt)

Then you need to install the Javascript grpc library dependency:

npm install grpc --save

You also need to copy the lnd rpc.proto file in your project directory (or at least somewhere reachable by your Javascript code).

The rpc.proto file is located in the lnrpc directory of the lnd sources.

In order to allow the auto code generated to compile the protos succucsfully, you'll need to comment out the following line:

//import "google/api/annotations.proto";

Let's now write some Javascript code that simply displays the getinfo command result on the console:

var grpc = require('grpc');

var lnrpcDescriptor = grpc.load("rpc.proto");

var lnrpc = lnrpcDescriptor.lnrpc;

var lightning = new lnrpc.Lightning('localhost:10009', grpc.credentials.createInsecure());

lightning.getInfo({}, function(err, response) {
	console.log('GetInfo:', response);
});

You just have to lauch your newly created Javascript file getinfo.js using nodejs:

node getinfo.js

You should get something like this in your console:

GetInfo: { identity_pubkey: '03c892e3f3f077ea1e381c081abb36491a2502bc43ed37ffb82e264224f325ff27',
  alias: '',
  num_pending_channels: 0,
  num_active_channels: 0,
  num_peers: 0,
  block_height: 1087612,
  block_hash: '000000000000024b2acc37958b15010057c6abc0a48f83c8dd67034bee2cb823',
  synced_to_chain: true,
  testnet: true }

With the above, you should have all the lnd related gRPC dependencies installed locally in your local project. In order to get up to speed with protofbuf usage from Javascript, see this official protobuf reference for Javascript. Additionally, this official gRPC resource details how to drive gRPC from node.js including the basics of making RPC calls, streaming RPC's (bi-directional and uni-directional), etc.