js 實現gridview全選

1.     function check(obj)
2.     {
3.       var flag=obj.checked;
4.       var gvshow=document.getElementById('gvshow');
5.       var count=gvshow.rows.length;
6.      
7.       for(var i=1;i<count;i++)
8.       { 
9.         //gvshow.rows[i].cells[0].firstChild.checked=flag;
10.         gvshow.rows[i].getElementsByTagName("input")[0].checked = flag; 
12.       }
13.     }