javascript获取页面滚动和可视的宽高

//网页被卷去的上高度
function EV_myScrollTop() {
  var n = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop || 0;
  return n;
}
//网页被卷去的左宽度
function EV_myScrollLeft() {
  var n = window.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft || 0;
  return n;
}
//网页可见区域宽
function EV_myClientWidth() {
  var n = document.documentElement.clientWidth || document.body.clientWidth || 0;
  return n;
}
//网页可见区域高
function EV_myClientHeight() {
  var n = document.documentElement.clientHeight || document.body.clientHeight || 0;
  return n;
}