如何修复我的应用程序中的此 WebSocket 错误？

Question

我下面有代理 WebSocket 连接的代码：

app.ws("/", async (socket) => {
    api = new WebSocket("wss://example.com/?v=2", [], {
        headers: {
            "Origin": "https://example.com"
        }
    });
    api.on("open", async () => {
        api.on("message", async data => socket.send(data.toString()));
        socket.on("message", async data => (api.readyState === api.OPEN) && api.send(data));
    });
});

但有时我会收到此错误：

C:\Users\admin\project\app.js:64
        socket.on("message", async data => (api.readyState === api.OPEN) && api.send(data));
                                                                                ^

TypeError: api.send is not a function

有没有办法在不使用 try catch 块的情况下解决这个问题？如果您能提供帮助，请用示例代码评论解决方案！

Answer 1

也许您可以确保 api 对象在尝试通过它发送消息之前已完全初始化并准备就绪。您可以通过在设置 socket.on("message") 处理程序之前检查 WebSocket 连接的就绪状态来完成此操作。像这样的东西应该有效，

app.ws("/", async (socket) => {
    let api;
    api = new WebSocket(
     ...
    )

    // wait for the WebSocket connection to open
    await new Promise(resolve => {
        api.on("open", resolve)
    })

    // then once the connection is open, set up the message handlers
    api.on("message", data => {
        socket.send(data.toString())
    })

    socket.on("message", data => {
        if (api.readyState === api.OPEN) {
            api.send(data);
        } else {
            // handle the case where the WebSocket connection is not open
            console.error("WebSocket connection is not open.")
        }
    })
})