/**

     * 判断是否是iphonex

     */

    function getIsIphonex () {

        var u = navigator.userAgent;

        var isIOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/);

        if (isIOS) {

            if (screen.height == 812 && screen.width == 375) {

                return true;

            }

            else {

                return false;

            }

        }

    };