Add xterm itegration

* Move to TypeScript from legacy JavaScript
* Add support of xterm.js
* Hterm is still available for backward compatibility

js/src/websocket.ts

@@ -0,0 +1,60 @@
+export class ConnectionFactory {
+    url: string;
+    protocols: string[];
+
+    constructor(url: string, protocols: string[]) {
+        this.url = url;
+        this.protocols = protocols;
+    };
+
+    create(): Connection {
+        return new Connection(this.url, this.protocols);
+    };
+}
+
+export class Connection {
+    bare: WebSocket;
+
+
+    constructor(url: string, protocols: string[]) {
+        this.bare = new WebSocket(url, protocols);
+    }
+
+    open() {
+        // nothing todo for websocket
+    };
+
+    close() {
+        this.bare.close();
+    };
+
+    send(data: string) {
+        this.bare.send(data);
+    };
+
+    isOpen(): boolean {
+        if (this.bare.readyState == WebSocket.CONNECTING ||
+            this.bare.readyState == WebSocket.OPEN) {
+            return true
+        }
+        return false
+    }
+
+    onOpen(callback: () => void) {
+        this.bare.onopen = (event) => {
+            callback();
+        }
+    };
+
+    onReceive(callback: (data: string) => void) {
+        this.bare.onmessage = (event) => {
+            callback(event.data);
+        }
+    };
+
+    onClose(callback: () => void) {
+        this.bare.onclose = (event) => {
+            callback();
+        };
+    };
+}