<script type="text/javascript">
function diva(){
document.getElementById('div1').style.display="none";
};
function divb(){
document.getElementById('div1').style.display="";
};
</script>
<div style="width:200px;height:200px;border:5px solid #000" id="div1"></div>
<input onClick="return diva()" type="button" value="是" />
<input onClick="return divb()" type="button" value="否" />