新增 event ， 优化 websocket

examples/js_ws_event/event.js

@@ -0,0 +1,23 @@
+let name=request.getQuery("name")
+if (name===""){
+    throw Error(`Missing name "${name}"`)
+}
+let ws = websocket();
+event.subscribe("messages").on(function (msg){
+    ws.writeText(msg)
+})
+let shouldExit = false;
+while (!shouldExit) {
+    let data = ws.readText();
+    switch (data) {
+        case "exit":
+            shouldExit = true;
+            break;
+        default:
+            event.put("messages",JSON.stringify({
+                name:name,
+                data:data
+            }));
+            break;
+    }
+}