判断浏览器是不是微信

   function isWeiXin() {    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;    } else {        return false;    }}// 使用方法    if (isWeiXin()) {        console.log(" 是来自微信内置浏览器")          } else {        console.log("不是来自微信内置浏览器")    }