[html5]记一些html5的东西

1级标题代表标签
2级标题代表属性

input

form

这里是MDN上面的解释

The form element that the input element is associated with (its form owner). The value of the attribute must be an id of a element in the same document. If this attribute is not specified, this element must be a descendant of a element. This attribute enables you to place elements anywhere within a document, not just as descendants of their form elements.

一般input标签都是放在form标签里面去提交的，但现在，允许将input标签放在任何地方，只要给input设置form属性，值为form标签的id值。

例如这样：

<form id="form" action="/">    <button>submit</button></form><input form="form" type="hidden" name="id" value="001">

这样点击submit按钮后，就会自动带上 id=001 这个参数了