screen.width / screen.height / innerWidth / innerHeight / clientWidth / clientHeight / scrollTop / scrollLeft / scrollHeight / scrollWidth

要取得螢幕的resolution有簡單的cross-browser的作法:
MDC Definition

window.screen.height: Returns the height of the screen in pixels.

MSDN Definition

Retrieves the vertical resolution of the screen.

scrollHeight/scrollWidth
MDC Definition

DOM:element.scrollHeight: DHTML property that gets the height of the scroll view of an element; it includes the element padding but not its margin.

MSDN Definition

Retrieves the scrolling height of the object.

YUI:

   var scrollHeight = (document.compatMode != 'CSS1Compat') ? document.body.scrollHeight : document.documentElement.scrollHeight;

YUI's getDocumentHeight / getDocumentWidth

/**
 * Returns the height of the document.
 * @method getDocumentHeight
 * @return {Int} The height of the actual document (which includes the body and its margin).
 */
getDocumentHeight: function() {
    var scrollHeight = (document.compatMode != 'CSS1Compat') ? document.body.scrollHeight : document.documentElement.scrollHeight;

    var h = Math.max(scrollHeight, Y.Dom.getViewportHeight());
    return h;
},

/**
 * Returns the width of the document.
 * @method getDocumentWidth
 * @return {Int} The width of the actual document (which includes the body and its margin).
 */
getDocumentWidth: function() {
    var scrollWidth = (document.compatMode != 'CSS1Compat') ? document.body.scrollWidth : document.documentElement.scrollWidth;
    var w = Math.max(scrollWidth, Y.Dom.getViewportWidth());
    return w;
},

YUI's getViewportHeight / getViewportWidth

/**
 * Returns the current height of the viewport.
 * @method getViewportHeight
 * @return {Int} The height of the viewable area of the page (excludes scrollbars).
 */
getViewportHeight: function() {
    var height = self.innerHeight; // Safari, Opera
    var mode = document.compatMode;

    if ( (mode || isIE) && !isOpera ) { // IE, Gecko
height = (mode == 'CSS1Compat') ?
document.documentElement.clientHeight : // Standards
document.body.clientHeight; // Quirks
    }

    return height;
},

/**
 * Returns the current width of the viewport.
 * @method getViewportWidth
 * @return {Int} The width of the viewable area of the page (excludes scrollbars).
 */

getViewportWidth: function() {
    var width = self.innerWidth;  // Safari
    var mode = document.compatMode;
    
    if (mode || isIE) { // IE, Gecko, Opera
width = (mode == 'CSS1Compat') ?
document.documentElement.clientWidth : // Standards
document.body.clientWidth; // Quirks
    }
    return width;
},

viewport code from PPK

var x,y;
if (self.innerHeight) // all except Explorer
{
 x = self.innerWidth;
 y = self.innerHeight;
}
else if (document.documentElement && document.documentElement.clientHeight)
 // Explorer 6 Strict Mode
{
 x = document.documentElement.clientWidth;
 y = document.documentElement.clientHeight;
}
else if (document.body) // other Explorers
{
 x = document.body.clientWidth;
 y = document.body.clientHeight;
}

How much the page has scrolled.

var x,y;
if (self.pageYOffset) // all except Explorer
{
 x = self.pageXOffset;
 y = self.pageYOffset;
}
else if (document.documentElement && document.documentElement.scrollTop)
 // Explorer 6 Strict
{
 x = document.documentElement.scrollLeft;
 y = document.documentElement.scrollTop;
}
else if (document.body) // all other Explorers
{
 x = document.body.scrollLeft;
 y = document.body.scrollTop;
}

Reference:
JavaScript - Window manipulation
Viewport introduction
Viewport - Properties