js--判断当前环境是否为app环境

    /**
     *判断是否是app环境
     */
    function getIsApp () {
        var ua = navigator.userAgent.toLowerCase();
        if (ua.match(/isapp/i) == "isapp") {
            return true;
        }
        return false;
    };

js--判断当前环境是否为微信环境

    /**
     * 判断是否是微信环境
     */
    function getIsWxClient () {
        var ua = navigator.userAgent.toLowerCase();
        if (ua.match(/MicroMessenger/i) == "micromessenger") {
            return true;
        }
        return false;
    };

h5判断是否为iphonex

function isIPhoneX(fn){
    var u = navigator.userAgent;
    var isIOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/); //ios终端
    if (isIOS) {        
        if (screen.height == 812 && screen.width == 375){
            //是iphoneX
        }else{
            //不是iphoneX
        } 
    }
}

参考地址：

https://www.cnblogs.com/wangyuyuan/p/9599646.html

https://www.cnblogs.com/wangyuyuan/p/9909492.html