javascript code to get the height of the page and the position of the scroll bar_javascript skills

var Viewport={
top : function(){
return window.pageYOffset
|| document.documentElement && document.documentElement.scrollTop
|| document.body.scrollTop;
},
height : function(){
return window.innerHeight
|| document.documentElement && document.documentElement.clientHeight
|| document.body.clientHeight;
},
left : function(){
return window.pageXOffset
|| document.documentElement && document.documentElement.scrollLeft
|| document.body.scrollLeft;
},
width : function(){
return window.innerWidth
|| document.documentElement && document.documentElement.clientWidth
|| document.body.clientWidth;
},
right : function(){
return Viewport.left() Viewport.width();
},
bottom : function(){
return Viewport.top() Viewport.height();
}
};

style.position="absolute";
style.left=50%;
style.top=Viewport.Top() Viewport.Height()/2 "px";