<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>
<input type="button" id="b" value="确定"><br><br>
<a href="javascript:;" onclick="change_click();return false;">点击修改button的click事件</a>
<script src="js/jquery.js" type="text/javascript"></script>
<script type="text/javascript">
$(function(){
    $("#b").bind('click',click1);
});

function change_click()
{
  $("#b").unbind('click');
  $("#b").bind("click", click2);
}
function click1()
{
  alert(1);
}
function click2()
{
  alert(2);
}
</script>