下面代码成立，但是当 form name改写成form id或者使用div id,div name时均无法达到效果，麻烦懂的告知下为什么
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script>
function p(){
document.a.b.disabled=true;
}
</script>
</head>
<body>
<form name="a">
<button name="b" onclick="p()">点击测试</button>
</form>
</body>
</html>
