diff --git a/demo/server.js b/demo/server.js
index 2a48a21c..856dac9e 100644
--- a/demo/server.js
+++ b/demo/server.js
@@ -17,7 +17,8 @@ function startServer() {
   expressWs(app);
 
   var terminals = {},
-      logs = {};
+      unsentOutput = {},
+      temporaryDisposable = {};
 
   app.use('/xterm.css', express.static(__dirname + '/../css/xterm.css'));
   app.get('/logo.png', (req, res) => {
@@ -55,9 +56,9 @@ function startServer() {
 
     console.log('Created terminal with PID: ' + term.pid);
     terminals[term.pid] = term;
-    logs[term.pid] = '';
-    term.on('data', function(data) {
-      logs[term.pid] += data;
+    unsentOutput[term.pid] = '';
+    temporaryDisposable[term.pid] = term.onData(function(data) {
+      unsentOutput[term.pid] += data;
     });
     res.send(term.pid.toString());
     res.end();
@@ -77,7 +78,10 @@ function startServer() {
   app.ws('/terminals/:pid', function (ws, req) {
     var term = terminals[parseInt(req.params.pid)];
     console.log('Connected to terminal ' + term.pid);
-    ws.send(logs[term.pid]);
+    temporaryDisposable[term.pid].dispose();
+    delete temporaryDisposable[term.pid];
+    ws.send(unsentOutput[term.pid]);
+
 
     // unbuffered delivery after user input
     let userInput = false;
@@ -137,7 +141,7 @@ function startServer() {
     // WARNING: This is a naive implementation that will not throttle the flow of data. This means
     // it could flood the communication channel and make the terminal unresponsive. Learn more about
     // the problem and how to implement flow control at https://xtermjs.org/docs/guides/flowcontrol/
-    term.on('data', function(data) {
+    term.onData(function(data) {
       try {
         send(data);
       } catch (ex) {
@@ -153,7 +157,8 @@ function startServer() {
       console.log('Closed terminal ' + term.pid);
       // Clean things up
       delete terminals[term.pid];
-      delete logs[term.pid];
+      delete unsentOutput[term.pid];
+      delete temporaryDisposable[term.pid];
     });
   });