采集出来的代码

微信的js里面的 iframe 代码 

(function(){    

var iframe = document.getElementsByTagName('iframe');    

for (var i=0,il=iframe.length;i

var a = iframe[i];    

var src_ = a.getAttribute('src')||a.getAttribute('data-src')||"";    

if(!/http(s)*\:\/\/v\.qq\.com\/iframe\/(preview|player)\.html\?/.test(src_)){    

continue;    

}    

var vid = getQuery("vid",src_);    

if(!vid){    

continue;    

}    

vid=vid.replace(/^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g,"");    

a.removeAttribute('src');    

var obj = window.__getVideoWh(a),    

mydiv = document.createElement('img');    

mydiv.className = "img_loading";    

mydiv.src="data:image/gif;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQImWNgYGBgAAAABQABh6FO1AAAAABJRU5ErkJggg==";    

mydiv.setAttribute("data-vid",vid);    

mydiv.style.cssText = "width: " + obj.w + "px !important;height: " + obj.h + "px !important;";    

a.style.display = "none";    

insertAfter(mydiv,a);    

a.style.cssText += ";width: " + obj.w + "px !important;height: " + obj.h + "px !important;";    

a.setAttribute("width",obj.w);    

a.setAttribute("height",obj.h);    

a.setAttribute("data-vh",obj.vh);    

a.setAttribute("data-vw",obj.vw);    

a.setAttribute("data-src",location.protocol+"//v.qq.com/iframe/player.html?vid="+ vid + "&width="+obj.vw+"&height="+obj.vh+"&auto=0");    

}    

})();    

})();     

为什么会自动吧这串js代码采集过来了，有视频的时候就显示出来 没有视频的时候采集出来就是上面的代码 求解释