documentElement和body的区别?

Question

今天学习scrollHeight时候,在谷歌控制台发现document.documentElement.scrollHeight === document.body.scrollHeight返回的是true,我想知道documentElement和body的区别?

Answer 1

document.documentElement返回的是html元素，它是只读的。
body返回的就是body元素.

elem = document;

 doc = elem.documentElement;

 // Either scroll[Width/Height] or offset[Width/Height] or client[Width/Height], whichever is greatest

 // unfortunately, this causes bug #3838 in IE6/8 only, but there is currently no good, small way to fix it.

return Math.max(elem.body["scroll" + name], doc["scroll" + name], elem.body["offset" + name], doc["offset" + name], doc["client" + name]);

获取页面高度jquery是这么实现的，取几个的最大值能解决一些兼容性等的问题。