added some ui to send test msgs

Tests/MQTTnet.TestApp.AspNetCore2/wwwroot/app/app.ts

@@ -5,16 +5,52 @@ var client = connect('ws://' + location.host + '/mqtt',
         clientId: "client1",
     });
 
+window.onbeforeunload = () => {
+    client.end();
+};
+
+var publishButton = document.getElementById("publish");
+var topicInput = <HTMLInputElement>document.getElementById("topic");
+var msgInput = <HTMLInputElement>document.getElementById("msg");
+var stateParagraph = document.getElementById("state");
+var msgsList = <HTMLUListElement>document.getElementById("msgs");
+
+publishButton.onclick = click => {
+    var topic = topicInput.value;
+    var msg = msgInput.value;
+    client.publish(topic, msg);
+};
+
 client.on('connect', () => {
-    client.subscribe('presence');
+    client.subscribe('#', { qos: 0 }, (err, granted) => {
+        console.log(err);   
+    });
     client.publish('presence', 'Hello mqtt');
+
+    stateParagraph.innerText = "connected";
+});
+
+client.on("error", e => {
+    showMsg("error: " + e.message);
+});
+
+client.on("reconnect", () => {
+    stateParagraph.innerText = "reconnecting";
 });
 
 client.on('message', (topic, message) => {
-    // message is Buffer
-    console.log(message.toString());
+    showMsg(topic + ": " + message.toString());
 });
 
-window.onbeforeunload = () => {
-    client.end();
-};
+function showMsg(msg: string) {
+    //console.log(msg);
+
+    var node = document.createElement("LI");
+    node.appendChild(document.createTextNode(msg));
+
+    msgsList.appendChild(node);
+
+    if (msgsList.childElementCount > 20) {
+        msgsList.removeChild(msgsList.childNodes[0]);
+    }
+}