JavaScript-对通过websocket.onmessage接收的消息执行某些操作

简而言之，我试图通过从后端通过websocket向网页发送消息来操纵我的网页。当我的页面加载时，websocket连接就建立起来了。当我的页面关闭或刷新时，我的页面会切断连接。我的想法是，我的后端（aws lambda fn）将通过websocket向我的HTML页面发送一条消息，然后我将处理该消息。下面是一段代码片段，解释了这段简单但麻烦的代码：

window.onload = function() {
    socket = setupWebSocket();
    
};

window.addEventListener('beforeunload', function(event) {
    socket.close()
})

function setupWebSocket() {
    socket = new WebSocket("wss://*****.amazonaws.com/dev");

    socket.onmessage = function(event) {
        console.log(event) // This logs out fine

        // I want to now run this function with the event data
        // However, it won't let me. It says event is undefined
        showTheList(event.data.urls);
    }
     
    return socket;
}


function showTheList(url_list) {
    // Do something with the list of urls
}

log（事件）生成以下日志

MessageEvent {isTrusted: true, data: "{"action": "show_images", "urls": ["https://*****"]}", origin: "wss://******.amazonaws.com", lastEventId: "", source: null, …}
bubbles: false
cancelBubble: false
cancelable: false
composed: false
currentTarget: WebSocket {url: "wss://********.amazonaws.com/dev", readyState: 1, bufferedAmount: 0, onopen: null, onerror: null, …}
data: "{"action": "show_images", "urls": ["https://*****/show?id=1020010095886C00", "https://*****/show?id=102001008CB55900", "https://*****/show?id=102001008E367000", "https://*****/show?id=103001009CAF3400", "https://*****/show?id=10400100534ADC00", "https://*****/show?id=102001008C81F600"]}"
defaultPrevented: false
eventPhase: 0
isTrusted: true
lastEventId: ""
origin: "wss://*****.amazonaws.com"
path: []
ports: []
returnValue: true
source: null
srcElement: WebSocket {url: "wss://*****.amazonaws.com/", readyState: 1, bufferedAmount: 0, onopen: null, onerror: null, …}
target: WebSocket {url: "wss://*****.amazonaws.com/", readyState: 1, bufferedAmount: 0, onopen: null, onerror: null, …}
timeStamp: 9330.839999951422
type: "message"
userActivation: null
__proto__: MessageEvent

---

您的数据似乎是字符串格式的

尝试替换：

showTheList(event.data.urls);

与：

showTheList(JSON.parse(event.data).urls);