SOURCE

$(function () {
    $('input:button').click(function(){
        let num = getNum()
        let name = $("input:eq(0)").val()
        let cls = $("input:eq(1)").val()
        let score = $("input:eq(2)").val()
        let node = $('<tr><td> '+num+'</td><td>' + name + '</td><td>'
        + cls + '</td><td>' + score + '</td><td><button onclick= "del(this)">删除</button></td></tr>"')
        $('tbody'). append(node)
        
    })
})
function del(obj){
    console. log($(obj). parent(). parent())
    $(obj).parent() . parent(). remove()
}
function getNum(){
    return $('tbody' ). children(). length+1
}

<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<form>
   
    <input placeholder="姓名"/>
    <input placeholder="班级"/>
    <input placeholder="成绩"/>
    <input type="button" value="添加"/>
</form>
<table border=1 >
    <thead>
        <tr>
            <th>编号</th>
            <th>姓名</th>
            <th>班级</th>
            <th>成绩</th>
            <th>操作</th>
        </tr>
    </thead>
<tbody>
</tbody>