使用 js 测试 websocket 连接

参考：https://blog.csdn.net/linysuccess/article/details/109223712

配合上篇文章，代码如下：

<!DOCTYPE html>
<html lang="zh-cn">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>WebSocket测试</title>
    <script>
        function initWebSocket(wsUri) {
            var websocket = new WebSocket(wsUri);
            websocket.onopen = function(evt) {
                console.log('连接建立中... '+wsUri);
            };
            websocket.onclose = function(evt) {
                console.log('连接关闭中...', evt);
            };
            websocket.onmessage = function(evt) {
                console.log('收到来自服务端的消息：', evt.data);
            };
            websocket.onerror = function(evt) {
                console.log('发生错误...', evt);
            };
            return websocket;
        }
    
        // 在此配置 websocket 的地址
        var websocket = initWebSocket("ws://localhost:8020/ws");
        var msg, i = 0;
        var loop = setInterval(function(){
            msg = "Hello " + (i++);
            if(websocket.readyState == WebSocket.OPEN) {
                websocket.send(msg);
                console.log('已发送消息：' + msg);
            } else {
                clearInterval(loop);
                console.log('连接已关闭，拜拜~');
            }
        }, 3000);
    </script>
</head>
<body>
    请按 F12 打开控制台查看消息
</body>
</html>