swoole websocket 出错Failed to construct ‘WebSocket’: The URL’s scheme must be either ‘ws’ or ‘wss’.

swoole websocket 可以跟客户端建立长连接，
在 js 中连接 swoole websocket 时，
出现下面的错误提示：

Failed to construct ‘WebSocket’: The URL ‘192.168.1.250:9876’ is invalid

Uncaught DOMException: Failed to construct ‘WebSocket’: The URL’s scheme must be either ‘ws’ or ‘wss’. ‘http’ is not allowed.

意思是要使用 ws或wss协议，
不能使用 http

原因在 js 中没有写协议导致，
修改好即可

var wsUrl = 'ws://192.168.1.250:9876';