用datalist标签来给输入框提供一个选择（但是该属性不兼容IE9，只兼容到ie10及ie10+）；
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>list属性示例</title>
</head>
<body>
text: <input type="text" name="greeting" list="greetings">
<!-- 使用style="display:none;"将datalist元素设定为不显示 -->
<datalist id="greetings" style="display:none;">
<option value="Good Morning">Good Morning</option>
<option value="Hello">Hello</option>
<option value="Good Afternoon">Good Afternoon</option>
</datalist>
</body>
</html>