Here are the frequently asked questions about Ant Design and antd that you should look up before you ask in the community or create a new issue. We also maintain a [FAQ issues label](http://u.ant.design/faq) for common github issues.
There is currently no plan to add support for Sass/Stylus(etc.) style files, but using tools on Google you can easily convert the provided Less files to your desired style format.
## Is there a difference between undefined and null in the controlled components of antd?
**Yes. antd will treats `undefined` as uncontrolled but `null` as controlled components which means empty value of it.**
As input element, React treats both `undefined` and `null` as uncontrolled. When the `value` is converted from a valid value to `undefined` or `null`, the component is no longer controlled, which causes some unexpected cases.
But in antd, `undefined` is treated as uncontrolled, and `null` is used as an explicit empty value of controlled components. To deal with some cases (e.g. `allowClear`) like clearing the `value` when the `value` is non-primitive. If you need a component controlled with the `value` valid, just set the `value` as `null`.
Note: For `options` in `Select-like` components, it is **strongly recommended not** to use `undefined` and `null` as `value` in `option`. Please use `string | number` as a valid `value` in `option`.
This is an old bug that has been fixed since `v3.11.x`. If you're using an older version, you can use `<Select getPopupContainer={trigger => trigger.parentElement}>` to render a component inside Popover. (Or other `getXxxxContainer` props)
Use `<Select getPopupContainer={trigger => trigger.parentElement}>` ([API reference](/components/select/#Select-props)) to render a component inside the scroll area. If you need to config this globally in your application, try `<ConfigProvider getPopupContainer={trigger => trigger.parentElement}>` ([API reference](/components/config-provider/#API))
While you can override a component's style, we don't recommend doing so. antd is not only a set of React components, but also a design specification as well.
The `defaultXxxx` (e.g. `defaultValue`) of `Input`/`Select`(etc...) only works on the first render. It is a specification of React. Please read [React's documentation](https://facebook.github.io/react/docs/forms.html#controlled-components).
antd use shallow compare of props to optimize performance. You should always pass the new object when updating the state. Please ref [React's document](https://reactjs.org/docs/thinking-in-react.html)
Yes, antd is designed to help you develop a complete background application. To do so, we override some global styles for styling convenience, and currently these cannot be removed or changed. More info at https://github.com/ant-design/ant-design/issues/4331 .
Please check [Ant Design Mobile](http://mobile.ant.design) as a possible solution, as `antd` has not been optimized to work well on mobile. You can also try the [react-component](https://github.com/react-component/) repositories which start with 'm-' 'rn-', which are also designed for mobile.
Yes, you can [import `antd` with script tag](https://ant.design/docs/react/introduce#Import-in-Browser), but we recommend using `npm` to import `antd`, as it is simple and easy to maintain.
If you need some features which should not be included in antd, try to extend antd's component with [HOC](https://gist.github.com/sebmarkbage/ef0bf1f338a7182b6775). [more](https://medium.com/@dan_abramov/mixins-are-dead-long-live-higher-order-components-94a0d2f9e750#.eeu8q01s1)
In a real world development, you may need a `YearPicker`, `MonthRangePicker` or `WeekRangePicker`. You are trying to add `mode` to `DatePicker`/`RangePicker` expected to implement those pickers. However, the `DatePicker`/`RangePicker` cannot be selected and the panels won't close now.
Like [the explaination](https://github.com/ant-design/ant-design/issues/11586#issuecomment-429189877) explains, this is because `<DatePicker mode="year" />` does not equal the `YearPicker`, nor is `<RangePicker mode="month" />` equal to `MonthRangePicker`. The `mode` property was added to support [showing time picker panel in DatePicker](https://github.com/ant-design/ant-design/issues/5190) in antd 3.0, which simply controls the displayed panel, and won't change the original date picking behavior of `DatePicker`/`RangePicker` (for instance you will still need to click date cell to finish selection in a `DatePicker`, whatever the `mode` is).
Likewise，`disabledDate` [cannot work on year/month panels](https://github.com/ant-design/ant-design/issues/9008#issuecomment-358554118) of `<DatePicker mode="year/month" />`, but only on cells of date panel.
You can refer to [this article](https://juejin.im/post/5cf65c366fb9a07eca6968f9) or [this article](https://www.cnblogs.com/zyl-Tara/p/10197177.html), using `mode` and `onPanelChange` to encapsulate a `YearPicker` or `MonthRangePicker` for your needs.
Or you can simply upgrade to [antd@4.0](https://github.com/ant-design/ant-design/issues/16911), in which we [added more XxxPickers](https://github.com/ant-design/ant-design/issues/4524#issuecomment-480576884) to meet those requirements, and `disabledDate` could be effect on those pickers too.
Static methods like message/notification/Modal.confirm are not using the same render tree as `<Button />`, but rendered to independent DOM node created by `ReactDOM.render`, which cannot access React context from ConfigProvider. Consider two solutions here:
1. Replace original usages with [message.useMessage](/components/message/#components-message-demo-hooks), [notification.useNotification](/components/notification/#Why-I-can-not-access-context,-redux,-ConfigProvider-locale/prefixCls-in-notification) and [Modal.useModal](/components/modal/#Why-I-can-not-access-context,-redux,-ConfigProvider-locale/prefixCls-in-Modal.xxx).
You should only access the API by official doc with ref. Directly access internal `props` or `state` is not recommended which will make your code strong coupling with current version. Any refactor will break your code like refactor with [Hooks](https://reactjs.org/docs/hooks-intro.html) version, delete or rename internal `props` or `state`, adjust internal node constructor, etc.
