为什么 JavaScript "window.postMessage" 创建重复消息?

Why does JavaScript "window.postMessage" create duplicate messages?

我正在尝试打开一个弹出窗口 window,做一些事情,然后将消息发送回开头 window 这样我就可以用它发送的数据做更多事情。

本质上,我正在改编the process outlined here

这是我关于“开场window”的代码。单击社交连接按钮时 运行s。该代码打开一个弹出窗口 window 并在打开 window 时分配一个侦听器事件以接收来自弹出窗口的消息:

//Do the operation
let windowObjectReference = null;
let previousUrl = null;

const openSignInWindow = (url, name) => {

    // remove any existing event listeners
    window.removeEventListener('message', receiveMessage);

    // window features
    const strWindowFeatures =
        'toolbar=no, menubar=no, width=600, height=700, top=100, left=100';

    if (windowObjectReference === null || windowObjectReference.closed) {
        /* if the pointer to the window object in memory does not exist
         or if such pointer exists but the window was closed */
        windowObjectReference = window.open(url, name, strWindowFeatures);
    } else if (previousUrl !== url) {
        /* if the resource to load is different,
         then we load it in the already opened secondary window and then
         we bring such window back on top/in front of its parent window. */
        windowObjectReference = window.open(url, name, strWindowFeatures);
        windowObjectReference.focus();
    } else {
        /* else the window reference must exist and the window
         is not closed; therefore, we can bring it back on top of any other
         window with the focus() method. There would be no need to re-create
         the window or to reload the referenced resource. */
        windowObjectReference.focus();
    }

    // add the listener for receiving a message from the popup
    window.addEventListener('message', event => receiveMessage(event), false);

    // assign the previous URL
    previousUrl = url;

};


const receiveMessage = event => {
    // Do we trust the sender of this message? (might be different from what we originally opened, for example).
    if (event.origin !== websiteHomeUrlNoSlash) {
        return;
    }

    const { data } = event;
    console.log(data); //<--- THIS WHERE I'm SEEING DUPLICATES

};

//Invoke the function
openSignInWindow(url, name);

在弹出窗口中,用户登录到他们的社交帐户,然后被重定向到我的应用程序上的一个页面,下面的代码是 运行。该代码将一条消息发回到开头 window,然后关闭弹出窗口:

// Get the message data
const messageObj = {
    pluginReason: pluginReasonVar,
    displayName: displayNameVar,
    provider: providerVar,
};

if (window.opener) {
    // send them to the opening window
    window.opener.postMessage(messageObj, websiteHomeUrlNoSlash);
    // close the popup
    if (closePopup) {
        window.close();
    }
}

一切几乎都按预期工作。用户可以登录他们的社交帐户,所有重定向和弹出窗口的打开和关闭都可以正常工作。

问题:

如果用户在不刷新页面的情况下多次执行 Social Connect 过程,则打印到控制台的消息数据会越来越重复 运行。

例如:

Social Connect 进程每次 运行 都应该只打印一次。但不知何故,它在每个后续 运行.

上添加了一个副本

这种重复不断增加,直到用户刷新页面,从一开始倒计时。

我想在 console.log(data) 点做更多的数据操作,但是当它在每个后续 运行.

上创建重复副本时我不能这样做

如何阻止这种情况发生?

可能是监听事件没有分离?如果是这样,我该如何解决?

您已经创建了一个匿名方法 (event) => { } 作为包装器并将其附加到 addEventListener 方法。

window.addEventListener('message', event => receiveMessage(event), false);

无法删除

window.removeEventListener('message', receiveMessage);

要修复它,请进行如下更改:

window.addEventListener('message', receiveMessage, false);

同时,如果方法receiveMessage在每次关闭window时都丢失,最好将removeEventListener部分移到receiveMessage中。

const receiveMessage = (event)=> {
  window.removeEventListener('message', receiveMessage);
  // do something else
}