function page(n) {
// Wrap the window in a jQuery object
var w = $(window);
  // Get the size of a page
var pagesize = w.height();
// Get the current scrollbar position
var current = w.scrollTop();
// Set new scrollbar position n pages down
w.scrollTop(current + n*pagesize);
}

  

   

  

this script is from a book  he didn't work in Jsbin.