javascript 实现 checkbox 全选

<script type="text/javascript">


function checkAll()




...{


var el = document.getElementsByTagName('input');


var len = el.length;


for(var i=0; i<len; i++)




...{


if((el[i].type=="checkbox"))




...{


el[i].checked = true;


}




}


}


function clearAll()




...{


var el = document.getElementsByTagName('input');


var len = el.length;


for(var i=0; i<len; i++)




...{


if((el[i].type=="checkbox"))




...{


el[i].checked = false;


}




}


}


</script>

asp:CheckBox ID="CheckBox2" runat="server" Text="全选" onclick="if(this.checked==true) { checkAll(); } else { clearAll(); }" />