*Add websocket compatibility with readyState

src/socket.ts

@@ -70,7 +70,17 @@ export default class Socket extends Duplex {
     return this._connecting;
   }
 
-  get readyState(): string {
+  get readyState(): string | number {
+    if (this._emulateWebsocket) {
+      if (this._connecting) {
+        return 0;
+      } else if (this.readable && this.writable) {
+        return 1;
+      } else {
+        return 3;
+      }
+    }
+
     if (this._connecting) {
       return "opening";
     } else if (this.readable && this.writable) {