ajax全选、全不选、反选、单删/批删

<meta charset="utf-8">
<?php
//链接数据库
$link = mysqli_connect('127.0.0.1','root','root','mone');
//设置字符集
mysqli_query($link,'set names utf8');


//接收当前页
$page = empty($_GET['page'])?1:$_GET['page'];
//求出总条数
$sql = "select * from user";
$res = mysqli_query($link,$sql);
$count = mysqli_num_rows($res);
//每页显示多少条
$length = 3;
//求出总页数
$num_page = ceil($count/$length);
//偏移量
$limit = ($page-1)*$length;
//查询
$sql2 = "select * from user limit $limit,$length";
$res2 = mysqli_query($link,$sql2);
while($a=mysqli_fetch_assoc($res2)){
    $data['data'][] = $a;
}


$data['home_page'] = 1;
$data['prev_page'] = $page-1<1?1:$page-1;
$data['next_page'] = $page+1>$num_page?$num_page:$page+1;
$data['last_page'] = $num_page;

?>
<table>
    <tr>
        <th>选择</th>
        <th>ID</th>
        <th>用户名</th>
        <th>密码</th>
        <th>性别</th>
        <th>年龄</th>
        <th>班级</th>
        <th>手机</th>
        <th>编辑</th>
    </tr>
    <div id="main">
    <?php foreach($data['data'] as $k=>$v){ ?>
    <tr id="<?php echo $v['user_id'];?>">
        <td><input type="checkbox" name="check" value="<?php echo $v['user_id'];?>"></td>
        <td><?php echo $v['user_id'];?></td>
        <td><?php echo $v['username'];?></td>
        <td><?php echo $v['pwd'];?></td>
        <td><?php echo $v['sex'];?></td>
        <td><?php echo $v['age'];?></td>
        <td><?php echo $v['class_name'];?></td>
        <td><?php echo $v['phone'];?></td>
        <td>
            <a href="">修改</a>
        </td>
    </tr>
    <?php } ?>
</div>
</table>

<button onclick="fun1()">全选</button>
<button onclick="fun2()">全不选</button>
<button onclick="fun3()">反选</button>
<button onclick="fun4()">单删/批删</button>
<script>
    

    function fun1(){
        var check = document.getElementsByName('check');
        for(var i=0;i<check.length;i++){
            if(check[i].checked==false){
                check[i].checked=true;
            }
        }
    }

    function fun2(){
        var check = document.getElementsByName('check');
        for(var i=0;i<check.length;i++){
            if(check[i].checked==true){
                check[i].checked=false;
            }
        }
    }

    function fun3(){
        var check = document.getElementsByName('check');
        for(var i=0;i<check.length;i++){
            if(check[i].checked==true){
                check[i].checked=false;
            }else{
                check[i].checked=true;
            }
        }
    }

    function fun4(){
        var arr = document.getElementsByName('check');
        var ar = [];
        for(var i=0;i<arr.length;i++){
            if(arr[i].checked==true){
                ar.push(arr[i].value);
            }
        }

        var id = ar.toLocaleString();
        if(id==''){
            alert('请先选择一项');
            return false;
        }else{
            //ajax请求
            var ajax = new XMLHttpRequest();
            ajax.open("get","delete.php?id="+id);
            ajax.send();
            ajax.onreadystatechange=function(){
                if(ajax.readyState==4 && ajax.status==200){
                    //alert(ajax.responseText);
                    //成功
                    if(ajax.responseText==1){

                        for(var i=0;i<ar.length;i++){
                            var tr=document.getElementById(ar[i]);
                            tr.remove();
                        }

                    }
                }
            }
        }
    }
</script>

delete.php

<?php
//接收传值
$id = $_GET['id'];
//链接数据库
$link = mysqli_connect('127.0.0.1','root','root','mone');
//设置字符集
mysqli_query($link,'set names utf8');
//拼接sql
$sql = "DELETE FROM user WHERE user_id in ($id)";
if(mysqli_query($link,$sql)){
    echo 1;
}else{
    echo 2;
}