<script language=javascript>
//The first method
function selectall1()
{
var a = ("input");
if(a[0].checked==true){
for (var i=0; i<; i++)
if (a[i].type == "checkbox") a[i].checked = false;
}
else
{
for (var i=0; i<; i++)
if (a[i].type == "checkbox") a[i].checked = true;
}
}
//The second method
function selectall2() {
var tform = ['form1'];
for (var i=0;i<;i++)
{
var e = [i];
if ( == "checkbox")
= !;
}
}
//The third method, combining the above two methods
function selectall3()
{
var a = ("input");
for (var i=0; i<; i++)
if (a[i].type == "checkbox") a[i].checked =!a[i].checked;
}
//The fourth method
function selectall4(id){ //Distinguish with id
var tform=['form1'];
for(var i=0;i<;i++){
var e=[i];
if(=="checkbox" && ==id) =!;
}
}
//The fifth method
function selectall(theform,thename){ //Theform specified form, thename is the name attribute of checkbox
var tform=[theform];
("thewen").value='Anti-select';
for(var i=0;i<;i++){
var e=[i];
if(=='checkbox' && ==thename)=!;
}
}
</script>
<form name="form1" method="post" action="">
<input type="checkbox" name="sid" value="1" />
<input name="thes" type="button" onclick="javascript:selectall3()" value="Select All"/>
</form>