您可以使用CSS转换来获得该效果。只需将css代码添加到从js更改的元素中：

You can use CSS transitions to get that effect. Just add that css code into the element that is changed from js:

-webkit-transition: all 1s ease-in-out;
-moz-transition: all 1s ease-in-out;
-o-transition: all 1s ease-in-out;
-ms-transition: all 1s ease-in-out;
transition: all 1s ease-in-out;

每次更改任何样式值时，在css上使用该值时，该更改将从当前值更新为新值1s。

With that on css each time any style value is being changed that change is animated from current to new value by 1s.

它仅适用于现代浏览器。查看示例：点击

It works only on modern browsers. See an example: click