<!-- 把如下代码加入<body>区域中 -->
<SCRIPT LANGUAGE="JavaScript">
<!-- Begin
var checkflag = "false";
function check(field) {
if (checkflag == "false") {
for (i = 0; i < field.length; i++) {
field[i].checked = true;}
checkflag = "true";
return "什么都不选"; }
else {
for (i = 0; i < field.length; i++) {
field[i].checked = false; }
checkflag = "false";
return "选中所有"; }
}
// End -->
</script>
<form name=myform action="" method=post>
<table>
<tr><td>
<b>请选择下面的选项</b><br>
<input type=checkbox name=list value="1">Java<br>
<input type=checkbox name=list value="2">JavaScript<br>
<input type=checkbox name=list value="3">ASP<br>
<input type=checkbox name=list value="4">HTML<br>
<input type=checkbox name=list value="5">SQL<br>
<br>
<input type=button value="选中所有" onClick="this.value=check(this.form.list)">
</td></tr>
</table>
</form>