Chrome扩展：处理异步sendMessage。

Question

我正在研究提取元数据的chrome扩展。解析元数据的代码包含在内容脚本中。 background.js和content.js通过sendMessage请求和响应进行通信。我遇到了一个与sendMessage请求的异步性质有关的问题，我不知道如何解决它（甚至在阅读了关于该问题的讨论之后）。任何意见或方向将不胜感激。我怀疑我没有得到如何将这些转化为回调。

background.js：

function onContextClick(info, tab) {  
    if(info["selectionText"]){ 
    var x = getMeta(tab); 
    //do stuff with x  
    } 
} 

function getMeta (tab) { 
chrome.tabs.sendMessage(tab.id, {fetchTag: "meta,name,author,content"}, function(response) { 
    //alert(response.data); 
    //one thing I tired was to put my "do stuff" embedded here, but that didn't work either   
    return response.data; 
    }); 
} 

var menu_id = chrome.contextMenus.create({"title": "Get Meta", "contexts":["selection"], "onclick": onContextClick}); 

content.js：

function fetchTag(string) { 
    var param = string.split(","); 
    return $(param[0] + "["+param[1]+ "=\"" + param[2] + "\"]").attr(param[3]); 
    } 

chrome.extension.onMessage.addListener(
    function(request, sender, sendResponse) { 
    if (request.fetchTag.length > 0)   
    sendResponse({data: fetchTag(request.fetchTag)}); 
    }); 

Answer 1

您可以使用关闭。通过这种方式。

function onContextClick(info, tab) {  
    if(info["selectionText"]){ 
    getMeta(tab, function(x){ 
     console.log(x); 
     //do stuff with x 
    }); 
    } 
} 

function getMeta (tab, callback) { 
chrome.tabs.sendMessage(tab.id, {fetchTag: "meta,name,author,content"}, function(response) { 
    //alert(response.data); 
    //one thing I tired was to put my "do stuff" embedded here, but that didn't work either 
    callback(response.data); 
    }); 
}