做了个jquery ajax 的例子，一直返回404的错误，求指点

我在网上找的例子写的jquery ajax读取json，但一直返回404的错误 ，感觉我的URL没写错啊，不知道为什么，代码如下：<!DOCTYPE html>
  <html>  <head>
  <meta charset="UTF-8">
<script type="text/javascript" src="js/jquery-3.3.1.js"></script>
<script type="text/javascript" src="js/jquery-3.3.1.min.js"></script>  <script>
        $(function(){
            $(':input:eq(0)').click(function(){alert("in");
                $.ajax({
                    url: 'data.json',
                    type: 'get',
                    dataType: 'json',
                    success: function(datas){
                        var tbhtml = "<tr><th>姓名</th><th>年龄</th><th>性别</th></tr>";
                        for(var i = 0;i<datas.length;i++){
                                tbhtml+="<tr><td>"+datas[i].name+"</td><td>"+datas[i].age+"</td><td>"+datas[i].sex+"</td></tr>";
                        }                        $('table:eq(0)').html(tbhtml);
                    },
                    error: function(XMLHttpRequest, textStatus, errorThrown) {
                        alert(XMLHttpRequest.status);
                        alert(XMLHttpRequest.readyState);
                        alert(textStatus);
         }
                })
            })
        })
       </script>      <title>ajax获取json测试</title>
      </head>
      测试
      <body>
       <center>
       
            <table border="1px solid">
                <tr>
                    <th>姓名</th>
                    <th>年龄</th>
                    <th>性别</th>
                  </tr>
            </table>
            <input type="button" value="加载数据" />
        </center>      </body>      </html>
data.json[
    {
        "name": "zhangsan",
        "age": 18,
        "sex": "man"
    },
    {
        "name": "lisi",
        "age": 17,
        "sex": "man"
    },
    {
        "name": "wangwu",
        "age": 16,
        "sex": "man"
    }
]XMLHttpRequest.status =404
XMLHttpRequest.readyState = 4
textStatus = error