Javascript 的 property 和 attribute 。

http://stackoverflow.com/questions/17494432/javascript-element-value-vs-element-getattributevalue
http://my.oschina.net/u/1163293/blog/268262
This attribute's value, when read, is used to fill the element'svalueproperty.

That property is what you get afterwards when you useElement.valueand that's what changed by the user or most JavaScript functions. The attribute isn't changed when the user changes the value through the interface.

In short, you almost always want to useElement.valueand almost neverElement.getAttribute("value").

“.”出来的是 property ，“.getAttribute(...)”出来的是 attribute ；
attribute -> property ：同步。
property -> attribute ：某些浏览器可能会对标准 property / attribute 做反向同步，某些浏览器可能全同步，某些浏览器可能不同不。
等待 Firefox 和 IE 验证。
大致如此，但不绝对，详见 http://www.mxgw.info/coding/javascript-attribute-property.html 。