通过SocketTask wx.connectSocket(Object object）调用Websocket服务，当服务调用失败时，API仍然调用success回调方法。

let url = "ws://127.0.0.1:7070/ws";
wx.connectSocket({
  url: url,
  header: {
    'content-type': 'text/xml'
  },
  protocols: ['xmpp'],
  success: (message) => {
    console.log(`WebSocket connection to ${url} success.${JSON.stringify(message)}`);
  },
  fail: e => {
    throw new Error(`WebSocket connection to ${url} failed. ${e.errMsg}`);
  },
  complete: res => {
    console.log(`WebSocket connection to ${url} complete.`)
  }

日志：

WebSocket connection to ws://127.0.0.1:7070/ws success.{"socketTaskId":10,"errMsg":"connectSocket:ok"}

WebSocket connection to ws://127.0.0.1:7070/ws complete.