table的自动增加

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            font-size: 14px;
            -webkit-user-select: none;
        }

        .box {
            margin: 10px auto;
            padding: 20px;
            width: 100%;
            border: 1px solid darkcyan;

            border-radius: 5px;
            box-shadow: 3px 3px 10px 0 grey;
        }

        .box table {
            border-collapse: collapse;/*去除单元格个单元格之间的空隙*/
            border:1px solid #000;
        }

        .box thead tr {
            border:1px solid #000;
            height: 20px;
            line-height: 20px;
            text-align: center;
            /*background: cornflowerblue;*/
        }

        .box thead tr th {
            width: 100px;
            color: #000;
            border-bottom: 1px solid #cccccc;
            padding: 10px;

        }

        .box thead tr th {
            cursor: pointer;

        }

        .box tbody tr {
            height: 30px;
            line-height: 30px;
            text-align: center;
        }

        .box tbody tr td {
            border:1px solid #000;
            width: 100px;
        }

        /*.box tbody tr {*/
        /*background: lightblue;*/
        /*}*/
        input{
            width:100px;
        }

    </style>
</head>
<body>
<div class="box">
    <input type="button" value="添加型号" onclick="insertRow3()">
    <input type="button" value="添加参数" onclick="addRow()">
    <input type="button" value="添加标题" onclick="insertRow()">
    <table id="table_info3">
            <tr>
                <td id="td0"></td>
            </tr>
    </table>
</div>
</body>
</html>
<script src="jquery-3.1.1.min.js"></script>
<script>
    //添加型号
    function insertRow3() {
        //获取table对象
        var table = document.getElementById("table_info3");
        //找到要添加button的td，这里以表格第一行第一列为例子
        for(var i = 0; i<table.rows.length; i++){
            var trid = document.getElementById("td"+i);
            //alert(trid.colSpan);
            if(trid.colSpan!==1){
                trid.colSpan = trid.colSpan + 1;
            }else{
                var oTd2 = table.rows[i].insertCell();
                oTd2.innerHTML = "<input type='text'>";
                //alert(table.rows[i]);
            }

        }
    }
    //添加参数
    function addRow() {
        var table = document.getElementById("table_info3");
        id="td"+table.rows.length;
        var newTR = document.getElementById("table_info3").insertRow(document.getElementById("table_info3").rows.length);
        for(var i=0;i<table.rows[0].cells.length;i++){

            var newNameTD = newTR.insertCell();
        }
        newNameTD.setAttribute('id',id);

        //alert(newNameTD.getAttribute('id'));
        //newNameTD.innerHTML = "<input type='text'/>";
//       var newNameTD = newTR.insertCell();
//        newNameTD.innerHTML = "<input name='LastName' id='LastName' type='text' />";
    }
    //添加标题
    function insertRow() {
        var table = document.getElementById("table_info3");
        id="td"+table.rows.length;
        var oTable = document.getElementById("table_info3");
        var oTr = oTable.insertRow();
        var oTd = oTr.insertCell();
        oTd.setAttribute('id',id);
        oTd.innerHTML = "<input type='text'/>";
        oTd.setAttribute('colspan',table.rows[0].cells.length);

    }
    function add(a){
        a=Number(a)+1;
        return a;
    }
</script>