fix(memorystore): Fix outdated nodejs example for Memorystore for Redis.

Author: craig08

memorystore/redis/server.js

@@ -20,22 +20,32 @@ const redis = require('redis');
 const REDISHOST = process.env.REDISHOST || 'localhost';
 const REDISPORT = process.env.REDISPORT || 6379;
 
-const client = redis.createClient(REDISPORT, REDISHOST);
+const client = redis.createClient({
+  url: `redis://${REDISHOST}:${REDISPORT}`,
+});
+
 client.on('error', err => console.error('ERR:REDIS:', err));
 
-// create a server
+client
+  .connect()
+  .then(() => {
+    console.log('Connected to Redis');
+  })
+  .catch(console.error);
+
 http
-  .createServer((req, res) => {
-    // increment the visit counter
-    client.incr('visits', (err, reply) => {
-      if (err) {
-        console.log(err);
-        res.status(500).send(err.message);
-        return;
-      }
+  .createServer(async (req, res) => {
+    try {
+      const reply = await client.incr('visits');
       res.writeHead(200, {'Content-Type': 'text/plain'});
       res.end(`Visitor number: ${reply}\n`);
-    });
+    } catch (err) {
+      console.error(err);
+      res.statusCode = 500;
+      res.end(err.message);
+    }
   })
-  .listen(8080);
+  .listen(8080, () => {
+    console.log('Server listening on port 8080');
+  });
 // [END memorystore_server_js]