SOURCE

$(()=>{
    $('input:button').click(()=>{
        let name = $("#name").val()
        let cls = $("#cls").val()
        let score = $("#score").val()

        let tr = $('<tr><td>'+ getNum() +'</td><td>' + name + '</td><td>' +
        cls + '</td><td>' + score + '</td><td>' +
        '<button onclick="del(this)">删除</button></td></tr>' )
       
       $('tbody').append(tr)
    })
})
function del(obj)
{
    $(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 id="name" placeholder="姓名"/>
    <input id="cls" placeholder="班级"/>
    <input id="score" placeholder="成绩"/>
    <input type="button" value="添加"/>
</form>
<table border=1 cellspacing=0 cellpadding=5>
    <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>
</table>