function calcViewportLocation(element) {
 var currentWindow = window;
 var rect = element.getBoundingClientRect(); // 元素的位置
 var top = rect.top;
 var left = rect.left;
 while (currentWindow.frameElement != null) { // 处理父级 Window
  element = currentWindow.frameElement;
  currentWindow = currentWindow.parent;
  rect = element.getBoundingClientRect();
  if (rect.top > 0) { top += rect.top; }
  if (rect.left > 0) { left += rect.left; }
 }
 return [Math.round(top), Math.round(left)];
}

function calcAbsolutLocation(element) {
 var top = 0;
 var left = 0;
 var currentWindow = window;
 while (element != null) {
  rect = element.getBoundingClientRect();
  var pageYOffset = currentWindow.pageYOffset;
  var pageXOffset = currentWindow.pageXOffset;
  if (typeof pageYOffset === 'undefined') { // IE8
   currentDocument = currentWindow.document;
   var bodyElement = (currentDocument.documentElement
     || currentDocument.body.parentNode || currentDocument.body);
   pageYOffset = bodyElement.scrollTop;
   pageXOffset = bodyElement.scrollLeft;
  }
  top += rect.top + pageYOffset;
  left += rect.left + pageXOffset;
  element = currentWindow.frameElement;
  currentWindow = currentWindow.parent;
  if (element != null) {
   style = window.getComputedStyle(element);
   top += parseInt(style.borderTopWidth, 10);
   left += parseInt(style.borderLeftWidth, 10);
  }
 }
 return [Math.round(top), Math.round(left)];
}