javascript - Chrome 扩展程序未收到响应

Question

这个问题已经有答案了:

Chrome Extension Message passing: response not sent (3 个回答)

已关闭 7 年前。

我试图获取从sendResponse到chrome.runtime.sendMessage的响应，但它总是显示未定义，下面是我的代码:

chrome.runtime.sendMessage(JSON.stringify(contact), function(response) {
    console.log('Response: ', response); // This is showing undefined
});

chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
   contact.addContact(request, function() {
      sendResponse({success: 'true'});
   });
});

因此，当我传递 sendResponse({success: true}) 时，应该在 chrome.runtime.sendMessage 的回调中收到它，但它显示未定义。

Answer 1

该问题可能是由于 contact.addContact 异步引起的。这意味着监听器在调用 sendResponse 之前结束。像这样从监听器返回 true 应该可以修复它:

chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
   contact.addContact(request, function() {
      sendResponse({success: 'true'});
   });
   return true;
});

来自documentation of chrome.runtime.onMessage :

sendResponse:

Function to call (at most once) when you have a response. The argument should be any JSON-ifiable object. If you have more than one onMessage listener in the same document, then only one may send a response. This function 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).