[JS代码]如何判断ipad或者iphone是否为横屏或者竖屏

      //判断横屏或者竖屏
        function orient() {
            //alert('gete');
            if (window.orientation == 0 || window.orientation == 180) {
                document.getElementById("os").innerHTML += "portrait";
                //$("body").attr("class", "portrait");
                orientation = 'portrait';
                return false;
            }
            else if (window.orientation == 90 || window.orientation == -90) {
                document.getElementById("os").innerHTML += "landscape";
               // $("body").attr("class", "landscape");
                orientation = 'landscape';

                return false;
            }
        }

window.onresize = function (){orient();}