关于checkbox全选和全撤的问题

 1<script language="javascript">   
 2function selectAll()   
 3{   
 4}   
 5  
 6function unSelectAll()   
 7{   
 8  
 9}   
10</script>

1<input type="checkbox" value="1"/>

1<input type="checkbox" value="2"/>

1<input type="checkbox" value="3"/>

1<input type="checkbox" value="4"/>

1<input type="checkbox" value="5"/>

1<input type="checkbox" value="6"/>

1<input onclick="selectAll()" type="button" value="全选"/>

1<input <form="" \---------------------------------------------------------------="" name="frm" onclick="unSelectAll()" type="button" value="全撤" 如何在javascript上实现全部选择和撤销全部选择=""/>

1<input name="m" type="checkbox"/>

1<input name="m" type="checkbox"/>

1<input name="m" type="checkbox"/>

1<input name="m" type="checkbox"/>

1<input name="m" type="checkbox"/>

1<input name="m" type="checkbox"/>

1<input name="m" type="checkbox"/>

1<input name="m" type="checkbox"/>

全选

1<input onclick="mm(this)" type="checkbox" value="Check All"/>

 1<script language="javascript">   
 2function mm(o)   
 3{   
 4var a = document.frm("m");   
 5for (var i=0; i<a.length; i++){   
 6a[i].checked = o.checked;   
 7}   
 8  
 9}   
10</script>

---------------------------------------------------------------

 1<html><body>
 2<script language="javascript">   
 3function selectAll()   
 4{   
 5var arrObj = document.all;   
 6for(var i = 0; i < arrObj.length;i++)   
 7{   
 8  
 9if(typeof arrObj[i].type != "undefined" && arrObj[i].type=='checkbox') arrObj[i].checked =true;   
10}   
11}   
12  
13function unSelectAll()   
14{   
15var arrObj = document.all;   
16for(var i = 0; i < arrObj.length;i++)   
17{   
18if(typeof arrObj[i].type != "undefined" && arrObj[i].type=='checkbox') arrObj[i].checked =false;   
19}   
20}   
21</script>
22<input type="checkbox" value="1"/>
23<input type="checkbox" value="2"/>
24<input type="checkbox" value="3"/>
25<input type="checkbox" value="4"/>
26<input type="checkbox" value="5"/>
27<input type="checkbox" value="6"/>
28<input onclick="selectAll()" type="button" value="È«Ñ¡"/>
29<input onclick="unSelectAll()" type="button" value="È«³·"/>
30</body>
31</html>

---------------------------------------------------------------

 1<script>   
 2function CheckAll()   
 3{   
 4for(var i=0;i<document.frmResult.elements.length;i++){   
 5var e=document.frmResult.elements[i];   
 6if (e.name != 'chkall')   
 7e.checked = document.frmResult.chkall.checked;   
 8}   
 9}   
10</script>

 1<form action="clear_fav.php" method="get" name="frmResult">
 2<input type="checkbox" value="1"/>
 3<input type="checkbox" value="2"/>
 4<input type="checkbox" value="3"/>
 5<input type="checkbox" value="4"/>
 6<input type="checkbox" value="5"/>
 7<input type="checkbox" value="6"/>
 8<br/>
 9<input name="chkall" onclick="CheckAll()" type="checkbox"/>   
10全部选中<br/>
11</form>