javascipt 小问题

Question

<table id="t1"><td><td>dddd</td></tr></table>
<br>
<input type=button onclick="t1.style.visibility='hidden'" value=hidden>
<input type=button onclick="t1.style.visibility='visible'" value=show>

Answer 1

<table id="t1"><td><td>dddd</td></tr></table>
<br>
<input type=button onclick="hors(this);" value=hidden>
<script>
function hors(obj){
obj.value=obj.value=='hidden'?'visible':'hidden';
t1.style.visibility=obj.value=='hidden'?'visible':'hidden';
}
</script>