layui表格怎么把表头固定

layui.use('flow', function () {

    var flow = layui.flow;

    flow.load({

        elem: '#LAY_demo1' //流加载容器

        , scrollElem: '#LAY_demo1' //滚动条所在元素，一般不用填，此处只是演示需要。

        , done: function (page, next) { //执行下一页的回调

            var fields = [];

            $.each($("input[type='hidden']"), function (i, o) {

                fields.push($(o).val());

            });

            var lis = [];

            $.ajax({

                type: 'POST',

                url: '${ctxPath}/zkEquipment/zkEquipmentReadingMode/' + page,

                success: function (res) {

                    $.each(res.data, function (index, item) {

                        var lisTr = [];

                        for (var i = 0; i < fields.length; i++) {

                            lisTr.push('<td>' + item[fields[i]] + '</td>');

                        }

                        var lisTd = lisTr.join('');

                        if (index + 1 == res.data.length) {

                            lis.push('<tr style="background-color: #1E9FFF">' + lisTd + '</tr>');

                        } else {

                            lis.push('<tr>' + lisTd + '</tr>');

                        }

                    });

                    next(lis.join(''), page < res.pages);

                    //解决th与td宽度不一致问题

                    var thArr = $("th");

                    var tdArr = $("tr").eq(1).find("td");

                    for (var i = 0; i < thArr.length; i++) {

                        $(thArr[i]).attr("width", $(tdArr[i]).outerWidth());

                    }

                    //设置高度

                    $("tbody").height($("body").height());

                }

            });

        }

    });

});