javascript - onMessageExternal.addListener 的回调可以是异步的吗？

Question

我有一个 Chrome 扩展程序和一个简单的网页一起运行。我向扩展程序发送一条消息，此时扩展程序会执行一些异步操作。下面的代码不起作用，因为 sendMessage 上的回调在我的 promise 解决之前立即触发。有没有办法解决？或者我是否需要手动将消息从扩展发送回浏览器？

网页:

chrome.runtime.sendMessage(editorExtensionId, {action: "share"}, function(response) {
    console.log(response);
  // var promise = navigator.mediaDevices.getUserMedia({audio:true, video:true});
});

扩展名:

chrome.runtime.onMessageExternal.addListener(function(request, sender, sendResponse) {
  var promise = new Promise((resolve, reject) => {
    if (request.action === 'share') {
      chrome.desktopCapture.chooseDesktopMedia(["screen","window"], (streamId, options) =>{
        resolve(streamId);
      });
    } else {
      reject('Bad action');
    }
  }).then(resp => {
    sendResponse(resp);
  });
});

Answer 1

根据documentation 、sendResponse 函数

becomes invalid when the event listener returns, unless you return true from the event listener to indicate you wish to send a response asynchronously (this will keep the message channel open to the other end until sendResponse is called)

因此，您的扩展代码将类似于:

chrome.runtime.onMessageExternal.addListener(function(request, sender, sendResponse) {
  var promise = new Promise((resolve, reject) => {
    if (request.action === 'share') {
      chrome.desktopCapture.chooseDesktopMedia(["screen","window"], (streamId, options) =>{
        resolve(streamId);
      });
    } else {
      reject('Bad action');
    }
  }).then(resp => {
    sendResponse(resp);
  });

  return true;  //<-- add this

});