多选checkbox

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script  src="jquery.min.js"></script>
</head>
<body>
    <form id='myForm' name="myForm" method="post" action="test6.php">
        <input type="checkbox" id='all'  >:全部</input>

       <input type="checkbox" class="list" name='list[]' value="1" >:1</input>

        <br/>
        <br/>
        <select name="select">
            <option>1</option>
            <option>2</option>
            <option>3</option>
        </select>
        <input type="button" id="but" value="sub"></input>
        <input type="submit" id="but" value="sub12"></input>
    </form>
</body>
</html>
<script type="text/javascript">
    $(document).ready(function($) {    
        $("#all").click(function(event) {
            if($('#all').prop('checked')){
                $('.list').prop('checked',true);
            }else{
                $('.list').prop('checked',false);
            }
        });
        $(".list").click(function(event) {
            var arr_stu = [];
            $('.list').each(function(index, el) {
                var statu = $(this).prop('checked');
                arr_stu.push(statu);
            });
            $.unique(arr_stu).length==1?$('#all').prop('checked',true):$('#all').prop('checked',false);
        });

        $('#but').click(function(){
            var data = $('#myForm').serialize();
            $.ajax({
                url: 'test6.php',
                type: 'post',
                dataType: 'json',
                data: data,
                success:function(result){

                }
            })
            
        })
    });
</script>