<div>A div</div>
<button>Get "blah" from the div</button>
<button>Set "blah" to "hello"</button>
<button>Set "blah" to 86</button>
<button>Remove "blah" from the div</button>
<p>The "blah" value of this div is <span>?</span></p>
我靠，老师你这样弄“The jQuery.data() method allows us to attach data of any type to DOM elements in a way that is safe from circular references and therefore from memory leaks. We can set several distinct values for a single element and retrieve them later:”，乍一看，会死人的
