questo e' quanto presente al riguardo in lightbox,
mi sembra faccia al caso tuo
codice:
// getPageSize()
// Returns array with page width, height and window width, height
// Core code from - quirksmode.com
// Edit for Firefox by pHaez
//
function getPageSize(){
var xScroll, yScroll;
if (window.innerHeight && window.scrollMaxY) {
xScroll = window.innerWidth + window.scrollMaxX;
yScroll = window.innerHeight + window.scrollMaxY;
} else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
xScroll = document.body.scrollWidth;
yScroll = document.body.scrollHeight;
} else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
xScroll = document.body.offsetWidth;
yScroll = document.body.offsetHeight;
}
var windowWidth, windowHeight;
// console.log(self.innerWidth);
// console.log(document.documentElement.clientWidth);
if (self.innerHeight) { // all except Explorer
if(document.documentElement.clientWidth){
windowWidth = document.documentElement.clientWidth;
} else {
windowWidth = self.innerWidth;
}
windowHeight = self.innerHeight;
} else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
windowWidth = document.documentElement.clientWidth;
windowHeight = document.documentElement.clientHeight;
} else if (document.body) { // other Explorers
windowWidth = document.body.clientWidth;
windowHeight = document.body.clientHeight;
}
// for small pages with total height less then height of the viewport
if(yScroll < windowHeight){
pageHeight = windowHeight;
} else {
pageHeight = yScroll;
}
// console.log("xScroll " + xScroll)
// console.log("windowWidth " + windowWidth)
// for small pages with total width less then width of the viewport
if(xScroll < windowWidth){
pageWidth = xScroll;
} else {
pageWidth = windowWidth;
}
// console.log("pageWidth " + pageWidth)
arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight)
return arrayPageSize;
}