求一段全选、反选、全取消的代码

 1<form name="aa">
 2<input type="checkbox"/>
 3<input type="checkbox"/>
 4<input type="checkbox"/>
 5<input type="checkbox"/>
 6<input type="checkbox"/>
 7<input type="checkbox"/>
 8<input onclick="selectAll(document.aa)" type="button" value="all"/>
 9<input onclick="selectOther(document.aa)" type="button" value="other"/>
10<input type="reset" value="reset"/>
11<script>   
12function selectAll(obj)   
13{   
14for(var i = 0;i<obj.elements.length;i++)   
15if(obj.elements[i].type == "checkbox")   
16obj.elements[i].checked = true;   
17}   
18function selectOther(obj)   
19{   
20for(var i = 0;i<obj.elements.length;i++)   
21if(obj.elements[i].type == "checkbox" )   
22{   
23if(!obj.elements[i].checked)   
24obj.elements[i].checked = true;   
25else   
26obj.elements[i].checked = false;   
27  
28}   
29}   
30</script>   
31\---------------------------------------------------------------   
32  
33全选document.execCommand('selectAll')   
34别的在找</form>