var ua = window.navigator.userAgent.toLowerCase();
    console.log(ua);//mozilla/5.0 (iphone; cpu iphone os 9_1 like mac os x) 
  applewebkit/601.1.46 (khtml, like gecko)version/9.0 mobile/13b143 safari/601.1
    if (ua.match(/MicroMessenger/i) == 'micromessenger') {
        return true; // 微信中打开
    } else {
        return false; // 普通浏览器中打开
    }