region = function(o){ var x = 0,y = 0,w = 0,h = 0; switch(o.length){ case 1: var r = region([]); var m = o[0]; var e = o[0]; w = m.offsetWidth; h = m.offsetHeight; if (m.getBoundingClientRect) { x = m.getBoundingClientRect().left + r.x - $([]).documentElement.clientLeft; y = m.getBoundingClientRect().top + r.y - $([]).documentElement.clientTop; } else { for (; m; x += m.offsetLeft, y += m.offsetTop, m = m.offsetParent); for (var e = e.parentNode; e && e != document.body; e = e.parentNode) { if (e.scrollTop) y -= e.scrollTop; if (e.scrollLeft)x -= e.scrollLeft; } } break; default: x = Math.max($([]).documentElement.scrollLeft,$([]).body.scrollLeft); y = Math.max($([]).documentElement.scrollTop,$([]).body.scrollTop); w = $([]).documentElement.clientWidth; h = $([]).documentElement.clientHeight; } return {'x':x,'y':y,'width':w,'height':h}; }
贴一张经典的示意图帮助理解:
