<script>
var checkflag="false";
function check(field){
if(checkflag=="false"){
for(i=0;i<field.length;i++){
field[i].checked=true;}
checkflag="true";
return "解除全选"; }
else {
for(i=0;i<field.length;i++) {
field[i].checked=false;}
checkflag="false";
return "选择全部";}}
</script>
<body>
<input type="button" name="SelectAll" value="全部选定" onclick="this.value=check(this.form)">
</body>
