识别XHR（AJAX）的反应，一边听HTTP响应在Firefox插件

问题描述

我有一个简单的Firefox插件（插件-SDK）监听到http resposes和盖帽，如果响应的内容类型匹配一组内容类型。现在，观察者监听所有的答复时，我没有兴趣听的图像，JavaScript文件和AJAX（XHR）的反应。我能以某种方式过滤掉或至少找出应对属于一个XHR请求，这样我就不会浪费在处理响应的资源。

类似的事情，可以实现在Chrome浏览器扩展，其中details.type可以main_frame，图像，XHR等。

  HTT presponseObserver =
{
  注意：功能（主题，主题数据）
  {

    如果（主题==HTTP上审视反应）
    {
        VAR渠道= subject.QueryInterface（Ci.nsIHttpChannel）;
        VAR的contentType;
        尝试 {
                的contentType = channel.getResponseHeader（Content-Type的'）;
                如果（/\b(?:xml|rss|javascript|vnd|json|html|text|image|ocsp|x-shockwave-flash)\b/.test(contentType））
                {
                    返回;
                }
            }
        赶上（错误）{
                返回;
            }
}
}
 

解决方案

要求从 nsIXMLHtt prequest 接口 notificationCallbacks

VAR isXHR;尝试{  VAR渠道= subject.QueryInterface（Ci.nsIHttpChannel）;  VAR回调= channel.notificationCallbacks;  VAR XHR =回调？ callbacks.getInterface（Ci.nsIXMLHtt prequest）：空;  isXHR = !! XHR;}赶上（E）{  isXHR = FALSE;}

I have a simple firefox addon (addon-sdk) which listens to http resposes and blocks if content type of response matches a set of content types. Now, the observer listens to all the responses when I am not interested in listening to image, javascript files and ajax (XHR) responses. Can I somehow filter out or atleast find out that response belongs to an XHR request so that I don't waste resources on processing the response.

The similar thing can be achieved in chrome extensions where "details.type" can be main_frame, image, xhr etc.

httpResponseObserver =  
{  
  observe: function(subject, topic, data)  
  {  

    if (topic == "http-on-examine-response") 
    {
        var channel = subject.QueryInterface(Ci.nsIHttpChannel); 
        var contentType;
        try {
                contentType = channel.getResponseHeader('Content-Type');
                if (/\b(?:xml|rss|javascript|vnd|json|html|text|image|ocsp|x-shockwave-flash)\b/.test(contentType))
                {
                    return;
                } 
            } 
        catch(error) {
                return;
            }
}
}

解决方案

Request the nsIXMLHttpRequest interface from notificationCallbacks

var isXHR;

try{
  var channel = subject.QueryInterface(Ci.nsIHttpChannel);
  var callbacks = channel.notificationCallbacks;
  var xhr = callbacks ? callbacks.getInterface(Ci.nsIXMLHttpRequest) : null;
  isXHR = !!xhr;
}
catch(e){
  isXHR = false;
}

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