<script>
function yincang(){
document.body.style="overflow-y:hidden;";
}
function huifu(){
document.body.style="overflow-y:auto;";
}
</script>
<div style="width:100%;height:3000px;text-align:center">
<input type=button onclick="yincang()" value="隐藏">&nbsp;&nbsp;&nbsp;&nbsp;
<input type=button onclick="huifu()" value="恢复">
</div>