1、on事件的绑定与解绑
<input type="button" value="点击显示" id="btn">
<input type="button" value="解绑" id="clear">
<script> <input type="button" val1、on事件的绑定与解绑
<input type="button" value="点击显示" id="btn">
<input type="button" value="解绑" id="clear">
<script> <input type="button" val