javascript - chrome 扩展 `sendResponse` 不起作用

Question

我正在编写 chrome 扩展，但 sendResponse 方法不起作用。

chrome.runtime.onMessage.addListener(
    function(request, sender, sendResponse) {

            if(!request.method){
                    return false;
            }

            if(request.method=='postList' && request.post_list){
                // alert(1);                                                                                                                                                                            
                    a_facebook_api.getPostFromDB(request.post_list, function(data){
                            alert(data);                                                                                                                                                              
                            sendResponse(data);                                                                                                                                                       
                          
                    });

            } else if(request.method=='postAdd' && request.post_data){
                    a_facebook_api.addPostToDB(request.post_data, function(data){

                            sendResponse(data);
                    });

    }

            return true;

}
);

 chrome.runtime.sendMessage({method: "postList",post_list: post_list}, function(response) {

         alert(response);
                                                                                                                                                           
            });

函数 alert(data) 有效。它为我提供了 JSON 格式的正确数据。但是，alert(response) 不显示任何消息。谁能告诉我为什么它不起作用？

提前致谢!

Answer 1

您还没有说明这段代码是否在内容脚本或后台页面中。通过查看它，我认为它是内容脚本的一部分。

我在我自己的一个扩展程序中尝试了您的代码，它提示“[object Object]”，当您提示一个不是字符串或数值的变量时会发生这种情况。如果您将警报数据更改为“response.responseData”，它会从后台页面提醒您标记为“responseData”的值。

因为它没有为您发出任何警报，我认为正在监听消息的脚本没有正确响应。

我让代码正常工作。 这是内容脚本:

//Document ready
window.onload = function() {
    alert('Ready');
    //Send a message
    sendMessage();
}

//Get message from background page
chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
    //Alert the message
    alert("The message from the background page: " + request.greeting);//You have to choose which part of the response you want to display ie. request.greeting
    //Construct & send a response
    sendResponse({
        response: "Message received"
    });
});

//Send message to background page
function sendMessage() {
    //Construct & send message
    chrome.runtime.sendMessage({
        method: "postList",
        post_list: "ThePostList"
    }, function(response) {
        //Alert the message
        alert("The response from the background page: " + response.response);//You have to choose which part of the response you want to display ie. response.response
    });
}

这是后台脚本:

//Get message from content script
chrome.runtime.onMessage.addListener(
    function(request, sender, sendResponse) {
        //Alert the message
        alert('The message from the content script: ' + request.method);//You have to choose which part of the response you want to display ie. request.method
        //Construct & send a response
        sendResponse({
            response: "Message received"
        });
    }
);

//Send message to content script
function sendDetails(sendData) {
    //Select tab
    chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
        //Construct & send message
        chrome.tabs.sendMessage(tabs[0].id, {
            greeting: sendData
        }, function(response) {
            //On response alert the response
            alert("The response from the content script: " + response.response);//You have to choose which part of the response you want to display ie. response.response
        });
    });
}

每次脚本收到消息时，您都必须使用“sendResponse”函数发送响应。

希望这对您有所帮助。