Use command line arguments more consistently

Author: murgatroid99

examples/metadata/client.js

@@ -242,15 +242,10 @@ const message = 'this is examples/metadata';
 
 async function main() {
   let argv = parseArgs(process.argv.slice(2), {
-    string: 'target'
+    string: 'target',
+    default: {target: 'localhost:50052'}
   });
-  let target;
-  if (argv.target) {
-    target = argv.target;
-  } else {
-    target = 'localhost:50051';
-  }
-  const client = new echoProto.Echo(target, grpc.credentials.createInsecure());
+  const client = new echoProto.Echo(argv.target, grpc.credentials.createInsecure());
   await unaryCallWithMetadata(client, message);
   await asyncWait(1000);
 

examples/metadata/server.js

@@ -142,9 +142,13 @@ const serviceImplementation = {
 };
 
 function main() {
+  const argv = parseArgs(process.argv.slice(2), {
+    string: 'port',
+    default: {port: '50052'}
+  });
   const server = new grpc.Server();
   server.addService(echoProto.Echo.service, serviceImplementation);
-  server.bindAsync('0.0.0.0:50051', grpc.ServerCredentials.createInsecure(), () => {
+  server.bindAsync(`0.0.0.0:${argv.port}`, grpc.ServerCredentials.createInsecure(), () => {
     server.start();
   });
 }