function deviceType(){

        var ua = navigator.userAgent;

        var agent = ["Android", "iPhone", "SymbianOS", "Windows Phone", "iPad", "iPod"];

        for(var i=0; i<len,len = agent.length; i++){

            if(ua.indexOf(agent[i])>0){

                break;

            }

        }

    }

    deviceType();

    window.addEventListener('resize', function(){

        deviceType();

    })

    微信的 有些不太一样

    function isWeixin(){

        var ua = navigator.userAgent.toLowerCase();

        if(ua.match(/MicroMessenger/i)=='micromessenger'){

            return true;

        }else{

            return false;

        }

    }