<script>
window.onload = function(){
selAll = document.getElementById("selAll");
hobbys = document.getElementsByName("hobby");
fx = document.getElementById("fx");
}
selAll.onclick = function(){
if(selAll.checked == true){
for(var i=0;i<hobbys.length;i++){
hobbys[i].checked = true;
}
}else{
for (var i = 0;i<hobbys.length;i++) {
hobbys[i].checked = false;
}
}
}
fx.onclick = function(){
for (var i = 0;i<hobbys.length;i++) {
var b = hobbys[i];
if(b.checked == true){
b.checked = false;
}else{
b.checked = true;
}
}
}
</script>
</head>
<body>
<input type="checkbox" name="" id="selAll" />全選
<button id="fx">反選</button>
<br />
<input type="checkbox" name="hobby" />籃球
<input type="checkbox" name="hobby" />足球
<input type="checkbox" name="hobby" />乒乓球
<input type="checkbox" name="hobby" />羽毛球
</body>