Chrome扩展：处理异步的sendMessage。 [英] Chrome Extension: dealing with asynchronous sendMessage.

问题描述

我工作的一个Chrome扩展，提取元数据。在code这解析元数据包含在一个内容脚本。该background.js和content.js通过的sendMessage请求和响应通信。我正在与请求的sendMessage的异步性的问题，我不知道如何解决它（甚至是阅读关于这一问题的讨论一连串之后）。任何意见或方向将是AP preciated。我怀疑我没有得到如何将这些进入回调。

background.js：

 函数onContextClick（资讯，标签）{
  如果（资讯[selectionText]）{
    VAR X = getMeta（卡）;
    //做的东西随x
  }
}功能getMeta（标签）{
chrome.tabs.sendMessage（tab.id，{fetchTag：元，名称，作者，内容}，函数（响应）{
    //alert(response.data）;
    //一件事我疲倦把我的做的东西在这里嵌入，但没有任何工作
    返回response.data;
    }）;
}VAR menu_id = chrome.contextMenus.create（{称号：获取元，语境：选择]，onclick事件：onContextClick}）;
 

content.js：

 函数fetchTag（串）{
    变种参数= string.split（，）;
    返回$（参数[0] +[+参数[1] += \\+参数[2] +\\]）ATTR（参数[3]）。
    }chrome.extension.onMessage.addListener（
  功能（要求，发件人，sendResponse）{
    如果（request.fetchTag.length大于0）
    sendResponse（{数据：fetchTag（request.fetchTag）}）;
  }）;
 

解决方案

您可以使用 关闭的。以这种方式

 函数onContextClick（资讯，标签）{
  如果（资讯[selectionText]）{
    getMeta（选项卡，功能（X）{
      的console.log（X）;
      //做的东西随x
    }）;
  }
}功能getMeta（标签，回调）{
chrome.tabs.sendMessage（tab.id，{fetchTag：元，名称，作者，内容}，函数（响应）{
    //alert(response.data）;
    //一件事我疲倦把我的做的东西在这里嵌入，但没有任何工作
    回调（response.data）;
    }）;
}
 

I'm working on a chrome extension that extracts meta data. The code which parses the metadata is contained in a content script. The background.js and content.js communicates via a sendMessage request and response. I'm running into an issue with the asynchronous nature of the sendMessage request and I'm not sure how to fix it (even after reading a litany of the discussions on the issue). Any advice or direction would be appreciated. I suspect I'm not getting how to turn these into callbacks.

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)});
  });

解决方案

You can use closures. In this way.

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);
    });
}

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