layer的弹出层获取不到数据

layer.open({
    type: 2,
    title: '添加',
    content: url.add_url,
    maxmin: true,
    area: ['600px', '90%'], // 宽 高
    btn: ['确定', '取消'],
    yes: function (index, layero) {
        var iframeWindow = window['layui-layer-iframe' + index],
            submitID = 'form-add',
            submit = layero.find('iframe').contents().find('#' + submitID);
        iframeWindow.layui.form.on('submit(' + submitID + ')', function (data) {
            $.ajax({});
        });
        submit.trigger('click'); // 触发表单提交
    }
});