function getelementleft(element) { var actualleft = element.offsetleft; var current = element.offsetparent; while (current!==null) { actualleft += current.offsetleft; current = current.offsetparent; } return actualleft; }
取得元素的左偏移量；
function getelementtop(element) { var actualtop = element.offsettop; var current = element.offsetparent; while (current!==null) { actualtop += current.offsettop; current = current.offsetparent; } return actualtop; }
取得元素的上偏移量；
利用offsetparent属性在dom层次中逐级向上回溯，将每个层次偏移量合计。