thinkphp 动态 级联

        <div class="form-item">
            <label class="item-label">一级分类<span class="check-tips"></span></label>
            <div class="controls">
                <select name="yijifenlei" id="yijifenlei">
                </select>
            </div>
        </div>
        <div class="form-item">
            <label class="item-label">二级分类<span class="check-tips"></span></label>
            <div class="controls">
                <select name="erjifenlei" id="erjifenlei">
                </select>
            </div>
        </div>

js代码：

    <script type="text/javascript">

　　　　　　　　　　　　var current_yijifenlei = {$info['yijifenlei']};
                    var current_erjifenlei = {$info['erjifenlei']};
                    $.post("{:U('getYijilist')}", function (result) {
                        var res = $.parseJSON(result);
                        $("#yijifenlei").prepend("<option value='0'>请选择</option>"); //为Select插入一个Option(第一个位
                        $.each(res, function (i, n) {
                            var select = '';
                            if (n.id == current_yijifenlei) {
                                select = 'selected';
                            }
                            $("#yijifenlei").append("<option value='" + n.id + "' " + select + ">" + n.yijimingcheng + "</option>"); //为Select追加一个Option(下拉项)
                        });
                    });
                    $.post("{:U('getErjilist')}", {yijiid: current_yijifenlei}, function (result) {
                        var res = $.parseJSON(result);
                        console.log(res)
                        $("#erjifenlei").prepend("<option value='0'>请选择</option>"); //为Select插入一个Option(第一个位
                        $.each(res, function (i, n) {
                            var select = '';
                            if (n.id == current_erjifenlei) {
                                select = 'selected';
                            }
                            $("#erjifenlei").append("<option value='" + n.id + "' " + select + ">" + n.erjimingcheng + "</option>"); //为Select追加一个Option(下拉项)
                        });
                    });
                    $('#yijifenlei').change(function () {
                        //alert($(this).children('option:selected').val());
                        $("#erjifenlei option").remove();
                        var fenlei1 = $(this).children('option:selected').val(); //这就是selected的值 
                        $.post("{:U('getErjilist')}", {yijiid: fenlei1}, function (result) {
                            var res = $.parseJSON(result);
                            if(fenlei1 >0)
                                $("#erjifenlei").prepend("<option value='0'>请选择</option>"); //为Select插入一个Option(第一个位
                            $.each(res, function (i, n) {
                                $("#erjifenlei").append("<option value='" + n.id + "' >" + n.erjimingcheng + "</option>"); //为Select追加一个Option(下拉项)
                            });
                        });
                    });
                });
    </script>

PHP代码：

    function getYijilist() {
        $yijilist = M('news_yijicaidanmeiju')->select();
        echo json_encode($yijilist);
    }
    function getErjilist() {
        $yijiid = I('yijiid', 0);
        if (!empty($yijiid)) {
            $map['yijiid'] = $yijiid;
            $erjilist = M('news_erjicaidanmeiju')->where($map)->select();
            echo json_encode($erjilist);
        } else {
            echo '[{"id":"0","erjimingcheng":"请选择"}]';
        }
    }