<form name="form">
<label for="input">姓名</label>
<input name="input"></input>
<span id="sp1">name is required</span>
<span id="sp2">max length is 10</span>
</form>
如何控制#sp1在未点击时隐藏，格式正确隐藏
sp2只有超出长度才显示