js怎样获取dpi

Question

用网上一些代码，
//获取DPI

function js_getDPI() {
    var arrDPI = new Array();
    if ( window.screen.deviceXDPI != undefined ) {
        arrDPI[0] = window.screen.deviceXDPI;
        arrDPI[1] = window.screen.deviceYDPI;
    }
    else {
        var tmpNode = document.createElement( "DIV" );
        tmpNode.style.cssText = "width:1in;height:1in;position:absolute;left:0px;top:0px;z-index:99;visibility:hidden";
        document.body.appendChild( tmpNode );
        arrDPI[0] = parseInt( tmpNode.offsetWidth );
        arrDPI[1] = parseInt( tmpNode.offsetHeight );
        tmpNode.parentNode.removeChild( tmpNode );
    }
    return arrDPI;
}

获取的都是96，不能区分啊

Answer 1

window.devicePixelRatio