DOM对象“各种”宽高距离属性

• clientWidth, clientHeight

• offsetWidth, offsetHeight

• scrollWidth, scrollHeight

• scrollLeft, scrollTop

• offsetTop, offsetLeft

clientHeight = height(200) + padding(10+10) = 220

offsetHeight = height(200) + padding(10+10) + border(5+5) = 230

scrollHeight = clientHeight + scrollTop

clientWidth = width(200) + padding(10+10) - 滚动条宽度(17) = 203

offsetWidth = width(200) + padding(10+10) + border(5+5) = 230

scrollWidth = clientWidth（没有水平滚动时）

offsetTop = 60 + 20 = 80

offsetLeft = 60 + 20 = 80（当前元素左上角在offsetParent节点内向左偏移的像素数）