问检查WebSocket服务器是否运行(在本地主机上)

EN

var wsFactory = { tryCount: 3,
                  connect : function(url){
                              var ctx = this,
                                  ws  = new WebSocket(url);

                              return new Promise(function(v,x){
                                                   ws.onerror   = e => { console.log(`WS connection attempt ${4-ctx.tryCount} -> Unsuccessful`);
                                                                         e.target.readyState === 3 && --ctx.tryCount;
                                                                         if (ctx.tryCount > 0) setTimeout(() => v(ctx.connect(url)), 1000);
                                                                         else x(new Error("3 unsuccessfull connection attempts"));
                                                                       };
                                                   ws.onopen    = e => { console.log(`WS connection Status: ${e.target.readyState}`);
                                                                         v(ws);
                                                                       };
                                                   ws.onmessage = m => console.log(m.data);
                                                 });
                            }
                };

wsFactory.connect("ws://localhost:8025/myContextRoot")
         .then(ws => ws.send("Hey..! This is my first socket message"))
         .catch(console.log);