function is_weixn_qq(){
var ua = navigator.userAgent.toLowerCase();
if(ua.match(/MicroMessenger/i)=="micromessenger") {
return "weixin";
} else if (ua.match(/QQ/i) == "qq") {
return "QQ";
}
return false;
}
微信内置浏览器的navigatoer.userAgent中包含了MicroMessenger字符串