# Front-end Development
Strapi's admin panel and plugins system aim to be an easy and powerful way to create new features.
The admin panel is a [React](https://facebook.github.io/react/) application which can embed other React applications. These other React applications are the `admin` parts of each Strapi's plugins.
## Environment setup
To enable local plugin development, you need to start your application with the front-end development mode activated:
```bash
$ cd my-app
$ yarn develop --watch-admin
```
## API
### Strapi global variable
The administration exposes a global variable that is accessible for all the plugins.
#### `strapi.backendURL`
Retrieve the back-end URL. (e.g. `http://localhost:1337`).
#### `strapi.currentLanguage`
Retrieve the administration panel default language (e.g. `en-US`)
#### `strapi.languages`
Array of the administration panel's supported languages. (e.g. `['ar', 'en', 'fr', ...]`).
#### `strapi.lockApp()`
Display a loader that will prevent the user from interacting with the application.
#### `strapi.unlockApp()`
Remove the loader so the user can interact with the application
#### `strapi.notification`
Display a notification (works with i18n message id). Use this command anywhere in your code.
```js
strapi.notification.error('app.notification.error');
strapi.notification.info('app.notification.info');
strapi.notification.success('app.notification.success');
strapi.notification.warning('app.notification.warning');
```
#### `strapi.remoteURL`
The administration url (e.g. `http://localhost:4000/admin`).
### Main plugin object
Each plugin exports all its configurations in an object. This object is located in `my-plugin/admin/src/index.js`
Here are its properties:
| key | type | Description |
| ------------------------- | ------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| blockerComponent | node | Props can be either `null` or React node (e.g. `() => `) |
| blockerComponentProps | object | Props to provide to customise the [blockerComponent](https://github.com/strapi/strapi/blob/58588e10e5d15921b0966e20ce1bc6cde70df5cc/packages/strapi-helper-plugin/lib/src/components/BlockerComponent/index.js#L81-L86) |
| description | string | Plugin's description retrieved from the package.json |
| id | string | Id of the plugin from the `package.json` |
| initializer | node | Refer to the [Initializer documentation](#initializer) |
| injectedComponents | array | Refer to the [Injected Component documentation](#injected-components) |
| isReady | boolean | The app will load until this proprety is true |
| leftMenuLinks | array | Array of links to inject in the menu |
| mainComponent | node | The plugin's App container, setting it to null will prevent the plugin from being displayed in the menu |
| name | string | The plugin's name retrieved from the package.json |
| pluginLogo | file | The plugin's logo |
| preventComponentRendering | boolean | Whether or not display the plugin's blockerComponent instead of the main component |
| settings | object | Refer to the [Plugins settings API](./frontend-settings-api.md) |
| reducers | object | The plugin's redux reducers |
| trads | object | The plugin's translation files |
### Initializer
The component is generated by default when you create a new plugin. Use this component to execute some logic when the app is loading. When the logic has been executed this component should emit the `isReady` event so the user can interact with the application.
:::note
Below is the Initializer component of the content-type-builder plugin.
It checks whether or not the auto-reload feature is enabled and depending on this value changes the mainComponent of the plugin.
:::
```js
/**
*
* Initializer
*
*/
import React from 'react';
import PropTypes from 'prop-types';
import pluginId from '../../pluginId';
class Initializer extends React.PureComponent {
// eslint-disable-line react/prefer-stateless-function
componentDidMount() {
const {
admin: { autoReload, currentEnvironment },
} = this.props;
let preventComponentRendering;
let blockerComponentProps;
if (currentEnvironment === 'production') {
preventComponentRendering = true;
blockerComponentProps = {
blockerComponentTitle: 'components.ProductionBlocker.header',
blockerComponentDescription: 'components.ProductionBlocker.description',
blockerComponentIcon: 'fa-ban',
blockerComponentContent: 'renderButton',
};
} else {
// Don't render the plugin if the server autoReload is disabled
preventComponentRendering = !autoReload;
blockerComponentProps = {
blockerComponentTitle: 'components.AutoReloadBlocker.header',
blockerComponentDescription: 'components.AutoReloadBlocker.description',
blockerComponentIcon: 'fa-refresh',
blockerComponentContent: 'renderIde',
};
}
// Prevent the plugin from being rendered if currentEnvironment === PRODUCTION
this.props.updatePlugin(pluginId, 'preventComponentRendering', preventComponentRendering);
this.props.updatePlugin(pluginId, 'blockerComponentProps', blockerComponentProps);
// Emit the event plugin ready
this.props.updatePlugin(pluginId, 'isReady', true);
}
render() {
return null;
}
}
Initializer.propTypes = {
admin: PropTypes.object.isRequired,
updatePlugin: PropTypes.func.isRequired,
};
export default Initializer;
```
### Injected Components
(Coming soon)
### Routing
The routing is based on the [React Router V5](https://reacttraining.com/react-router/web/guides/philosophy), due to it's implementation each route is declared in the `containers/App/index.js` file.
::: tip
Each route defined in a plugin must be prefixed by the plugin's id.
:::
**Route declaration :**
Let's say that you want to create a route `/user` with params `/:id` associated with the container UserPage.
The declaration would be as follows :
**Path —** `plugins/my-plugin/admin/src/containers/App/index.js`.
```js
import React from 'react';
import pluginId from '../../pluginId';
import UserPage from '../UserPage';
// ...
class App extends React.Component {
// ...
render() {
return (
);
}
}
// ...
```
### Styling
The administration panel uses [styled-components](https://styled-components.com/) for writing css.
### i18n
[React Intl](https://github.com/yahoo/react-intl) provides React components and an API to format dates, numbers, and strings, including pluralization and handling translations.
**Usage**
We recommend to set all your components text inside the translations folder.
The example below shows how to use i18n inside your plugin.
**Define all your ids with the associated message:**
**Path —** `./plugins/my-plugin/admin/src/translations/en.json`.
```json
{
"notification.error.message": "An error occurred"
}
```
**Path —** `./plugins/my-plugin/admin/src/translations/fr.json`
```json
{
"notification.error.message": "Une erreur est survenue"
}
```
**Usage inside a component**
**Path —** `./plugins/my-plugin/admin/src/components/Foo/index.js`.
```js
import { FormattedMessage } from 'react-intl';
import SomeOtherComponent from 'components/SomeOtherComponent';
const Foo = props => (
);
export default Foo;
```
See [the documentation](https://github.com/yahoo/react-intl/wiki/Components#formattedmessage) for more extensive usage.
### Global context
All plugins are wrapped inside the `GlobalContextProvider`, in this object you will have access to all plugins object as well as other utilities.
Usage:
**Inside a functional component:**
```js
import React from 'react';
import { useGlobalContext } from 'strapi-helper-plugin';
const Foo = () => {
const globalContext = useGlobalContext();
console.log(globalContext);
return Foo
;
};
```
**Inside a class component:**
```js
import React from 'react';
import { GlobalContext } from 'strapi-helper-plugin';
class Foo extends React.Component {
static contextType = GlobalContext;
render() {
console.log(this.context);
return Foo
;
}
}
```