I want to ask a newbie question, why does this table sorting output so many things when I click on the name in line 123? Shouldn't it be output 5 times? Why is it 15 times? Where did I go wrong {code...}

javascript - What's wrong with sorting this table-PHP Chinese Network Q&A

Ask a newbie question, why does this table sorting output so many things when I click on name in line 123? Shouldn't it be output 5 times? Why is it 15 times? Where did I go wrong?

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>表格排序</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        table {
            width: 700px;
            text-align: center;
            margin: 100px auto;
            border-radius: 10px;
            padding: 10px;
            box-shadow: 0 0 10px darkgreen;
            font-size: 20px;
        }

        table caption {
            line-height: 50px;
            font-size: 30px;
            font-weight: 700;
        }

        table thead {
            height: 40px;
            line-height: 40px;
            background: darkgreen;
            color: #ffffff;
        }

        table thead tr {
            -webkit-user-select: none;
        }

        table thead tr th.cursor {
            cursor: pointer;
        }

        table tbody tr {
            height: 40px;
            line-height: 40px;
        }

        table tbody tr.bg0 {
            background: lightcyan;
        }

        table tbody tr.bg1 {
            background: lightpink;
        }
    </style>
</head>
<body>
<table cellpadding="0" cellspacing="0" id="tab">
    <caption>表格排序</caption>
    <thead>
    <tr>
        <th class="cursor">name</th>
        <th class="cursor">age</th>
        <th class="cursor">level</th>
        <th>sex</th>
    </tr>
    </thead>
    <tbody>

    </tbody>
</table>
<script src="../utils.js"></script>
<!--<script src="js/tab1.js"></script>-->
</body>
</html>
<script>
    var oTab = document.getElementById("tab");
    var tHead = oTab.tHead;
    var tBody = oTab.tBodies[0];
    var aCells = tHead.rows[0].cells;
    var aRows = tBody.rows;
    var data = null;
    getData();
    function getData() {
        var xhr = new XMLHttpRequest();
        xhr.open("GET", "data.txt", true);
        xhr.send();
        xhr.onreadystatechange = function () {
            if (xhr.readyState === 4 && /^2\d{2}$/.test(xhr.status)) {
                data = utils.jsonParse(xhr.responseText);
                bindData();
            }
        }
    }
    function bindData() {
        var str = '';
        for (var i = 0; i < data.length; i++) {
            data[i].sex = data[i].sex == 0 ? "男" : "女";
            str += '<tr>\
                    <td>' + data[i].name + '</td>\
                    <td>' + data[i].age + '</td>\
                    <td>' + data[i].level + '</td>\
                    <td>' + data[i].sex + '</td>\
                </tr>'
        }
        tBody.innerHTML = str;
        changeColor();
    }
    function changeColor() {
        for (var i=0;i<aRows.length;i++){
            aRows[i].className='bg'+i%2;
        }
    }
    for (var i=0;i<aCells.length;i++){
        aCells[i].index=i;
        aCells[i].onclick=function () {
            sort(this.index);
        }
    }
    function sort(index) {
        var ary=utils.makeArray(aRows);
        ary.sort(function (a, b) {
            console.log(a,b);
            a=a.cells[index].innerHTML;
            b=b.cells[index].innerHTML;
            if(isNaN(a)||isNaN(b)){
                return b.localeCompare(a);
            }
            return a-b;
        });
        var frg=document.createDocumentFragment();
        for (var j=0;j<ary.length;j++){
            frg.appendChild(ary[j]);
        }
        console.dir(ary);
        tBody.appendChild(frg);
        changeColor();
    }
</script>