Lab 03 submission

app.js

@@ -0,0 +1,129 @@
+const express = require('express');
+const path = require('path');
+const EventEmitter = require('events');
+const chatEmitter = new EventEmitter();
+const port = process.env.PORT || 3000;
+
+const app = express();
+app.use(express.static(__dirname + '/public'));
+
+// app.get('/', respondText);
+app.get('/', chatApp);
+app.get('/json', respondJson);
+app.get('/echo', respondEcho);
+app.get('/chat', respondChat);
+app.get('/sse', respondSSE);
+
+/**
+ * This endpoint will respond to the client with a stream of server sent events
+ * @param {http.IncomingMessage} req
+ * @param {http.ServerResponse} res
+ */
+function respondSSE (req, res) {
+  res.writeHead(200, {
+    'Content-Type': 'text/event-stream',
+    'Connection': 'keep-alive',
+  });
+  console.log("testSSE");
+  const onMessage = message => res.write(`data: ${message}\n\n`); // use res.write to keep the connection open, so the client is listening for new messages
+  chatEmitter.on('message', onMessage);
+
+  res.on('close', () => {
+    chatEmitter.off('message', onMessage);
+  });
+}
+
+
+/**
+ * This endpoint will respond to the client with a stream of server sent events
+ * @param {http.IncomingMessage} req
+ * @param {http.ServerResponse} res
+ */
+function respondChat (req, res) {
+  const { message } = req.query;
+  console.log("test");
+  chatEmitter.emit('message', message);
+  res.end();
+}
+
+// note that typically the variables here are `req` and `res` but we are using `request` and `response` for clarity
+// modify the server code to look like this
+// const server = http.createServer(function(request, response) {
+//     const parsedUrl = url.parse(request.url, true);
+//     const pathname = parsedUrl.pathname;  
+
+//     if (pathname === '/') return respondText(request, response);
+//     if (pathname === '/json') return respondJson(request, response);
+//     if (pathname.match(/^\/echo/)) return respondEcho(request, response);
+
+//     respondNotFound(request, response);
+// });
+
+
+/**
+ * Responds with plain text
+ * 
+ * @param {http.IncomingMessage} req
+ * @param {http.ServerResponse} res
+ */
+function respondText(req, res) {
+    res.setHeader('Content-Type', 'text/plain');
+    res.end('hi');
+  }
+
+  /**
+   * Responds with JSON
+   * 
+   * @param {http.IncomingMessage} req
+   * @param {http.ServerResponse} res
+   */
+  function respondJson(req, res) {
+    // express has a built in json method that will set the content type header
+    res.json({
+      text: 'hi',
+      numbers: [1, 2, 3],
+    });
+  }
+
+/**
+ * Responds with the input string in various formats
+ * 
+ * @param {http.IncomingMessage} req
+ * @param {http.ServerResponse} res
+ */
+function respondEcho (req, res) {
+    // req.query is an object that contains the query parameters
+    const { input = '' } = req.query;
+
+    // here we make use of res.json to send a json response with less code
+    res.json({
+      normal: input,
+      shouty: input.toUpperCase(),
+      charCount: input.length,
+      backwards: input.split('').reverse().join(''),
+    });
+  }
+
+/**
+ * Serves up the chat.html file
+ * @param {http.IncomingMessage} req
+ * @param {http.ServerResponse} res
+ */
+function chatApp(req, res) {
+    res.sendFile(path.join(__dirname, '/chat.html'));
+  }
+
+/**
+ * Responds with a 404 not found
+ * 
+ * @param {http.IncomingMessage} req
+ * @param {http.ServerResponse} res
+ */
+function respondNotFound(req, res) {
+    res.writeHead(404, { 'Content-Type': 'text/plain' });
+    res.end('Not Found');
+  }
+
+  app.listen(port, () => {
+    console.log(`Listening on port ${port}`);
+  });