我认为我的问题已被修正

  chrome.tabs.sendMessage（tabId， {action：'test'}，
 

注意，我错误地使用 msg ，而不是 action 在上述问题中。 另外，我不使用第三个参数sendResponse以避免全双工通信
我只需将内容脚本中的另一条消息发送回后台页面。

从内容脚本中，使用以下命令将消息发送到后台页面：

 函数SendMessageToBackgroundPage（data）
 {
 chrome.runtime.sendMessage（{
 action：'功夫'，
来源：'熊猫'
}）; 

 

使用以下代码在背景页面中抓取它：

  chrome.runtime.onMessage.addListener（
函数（request，sender，sendResponse）{
 switch（request.action）{
'kungfu'：alert（request.source）; 
} 
}）; 
 

I was experimenting with chrome extension. My goal is to send a message from background script to injected script and let the injected script return back the result.

Code is as below:

background.js

chrome.tabs.onUpdated.addListener(function (tabId, changeInfo, tab){
    chrome.tabs.executeScript(tabId, {'file': "content.js"}, 
        function(){
            chrome.tabs.sendMessage(tabId, {msg: 'test'}, 
                function(response){
                    console.log(response);
                }
            );
            return true;
        }
    );
});

content.js

chrome.runtime.onMessage.addListener(
    function(request, sender, sendResponse) {
        sendResponse('test message');
        return true;
    }
);

I get the error message

Could not send response: The chrome.runtime.onMessage listener must return true if you want to send a response after the listener returns 

when calling sendResponse inside content.js

I am already returning true from the listener.. confused?
Am I missing something obvious?

I think my issue was fixed by

chrome.tabs.sendMessage(tabId, {action: 'test'}, 

Note, I incorrectly use msg instead of action in above question.

Also, I do not use the third parameter sendResponse to avoid full-duplex communication I simply post another message from content script back to background page.

From content script, send message to background page using:

function SendMessageToBackgroundPage(data)
{
    chrome.runtime.sendMessage({
        action: 'kungfu',
        source: 'panda'
    });
}

Catch it inside background page using:

chrome.runtime.onMessage.addListener(
        function(request, sender, sendResponse) {
            switch (request.action) {
                case 'kungfu': alert(request.source);
            }
        });