<script type="text/javascript">
function checkAll(form) {
if(form.elements[0].checked == true) {
for (i = 1, n = form.elements.length; i < n; i++) {
form.elements[i].checked = true; }
} else {
for (i = 1, n = form.elements.length; i < n; i++) {
form.elements[i].checked = form.elements[i].defaultChecked; } }
}
</script>
<form name="checkform" method="post" action="" />
<input type="checkbox" checked name="checker" onclick="checkAll(this.form);" /> 1
<input type="checkbox" checked name="2" /> 2
<input type="checkbox" checked name="3" /> 3
<input type="checkbox" checked name="4" /> 4
<input type="checkbox" checked name="5" /> 5
</form>