js生成table

<script type="text/javascript">
        window.onload = function() {
            var tab = document.getElementById("tab1");

            var tabInfo = Ajax.Ajax.GetCompanyInfoByType(1).value;

            if (tabInfo != null && tabInfo.Rows.length > 0) {
                for (var i = 0; i < tabInfo.Rows.length; i++) {
                    var tr = tab.insertRow();

                    var tb = tr.insertCell();
                    tb.style.background = "#ffffff";
                    tb.style.width = "30%";

                    tb.innerHTML = tabInfo.Rows[i]["Name"];

                    var tb = tr.insertCell();

                    tb.style.background = "#ffffff";

                    var tabChoose = Ajax.Ajax.GetCompanyInfoChooseByID(tabInfo.Rows[i]["ID"]).value;

                    var arr = new Array(tabChoose.Rows.length);

                    if (tabChoose != null && tabChoose.Rows.length > 0) {
                        for (var j = 0; j < tabChoose.Rows.length; j++) {
                            arr[j] = "<OPTION value = '" + tabChoose.Rows[j]["ID"] + "'>" + tabChoose.Rows[j]["Name"] + "</OPTION>";
                        }
                    }

                    tb.innerHTML = "<Select ID='" + tabInfo.Rows[i]["ID"] + "'>" + arr.join() + "</Select>";
                }
            }
            var tr = tab.insertRow();
            var tb = tr.insertCell();
            tb.style.background = "#ffffff";
            tb.style.colspan = "2";
            tb.setAttribute("colSpan", "2");
            tb.setAttribute("align", "center");
            tb.innerHTML = "<input id='btnSave' type='button' value='保存'/>";
        }
    </script>