The compose package is a collection of handy Hooks and Higher Order Components (HOCs) you can use to wrap your WordPress components and provide some basic features like: state, instance id, pure...
The compose function is an alias to flowRight from Lodash. It comes from functional programming, and allows you to compose any number of functions. You might also think of this as layering functions; compose will execute the last function first, then sequentially move back through the previous functions passing the result of each function upward.
An example that illustrates it for two functions:
const compose = ( f, g ) => x
=> f( g( x ) );Here's a simplified example of compose in use from Gutenberg's PluginSidebar component:
Using compose:
const applyWithSelect = withSelect( ( select, ownProps ) => {
return doSomething( select, ownProps);
} );
const applyWithDispatch = withDispatch( ( dispatch, ownProps ) => {
return doSomethingElse( dispatch, ownProps );
} );
export default compose(
withPluginContext,
applyWithSelect,
applyWithDispatch,
)( PluginSidebarMoreMenuItem );Without compose, the code would look like this:
const applyWithSelect = withSelect( ( select, ownProps ) => {
return doSomething( select, ownProps);
} );
const applyWithDispatch = withDispatch( ( dispatch, ownProps ) => {
return doSomethingElse( dispatch, ownProps );
} );
export default withPluginContext(
applyWithSelect(
applyWithDispatch(
PluginSidebarMoreMenuItem
)
)
);Install the module
npm install @wordpress/compose --saveThis package assumes that your code will run in an ES2015+ environment. If you're using an environment that has limited or no support for ES2015+ such as lower versions of IE then using core-js or @babel/polyfill will add support for these methods. Learn more about it in Babel docs.
For more details, you can refer to each Higher Order Component's README file. Available components are located here.
# compose
Composes multiple higher-order components into a single higher-order component. Performs right-to-left function composition, where each successive invocation is supplied the return value of the previous.
Parameters
- hocs
...Function: The HOC functions to invoke.
Returns
Function: Returns the new composite function.
# createHigherOrderComponent
Given a function mapping a component to an enhanced component and modifier name, returns the enhanced component augmented with a generated displayName.
Parameters
- mapComponentToEnhancedComponent
Function: Function mapping component to enhanced component. - modifierName
string: Seed name from which to generated display name.
Returns
WPComponent: Component class with generated display name assigned.
# ifCondition
Higher-order component creator, creating a new component which renders if the given condition is satisfied or with the given optional prop name.
Parameters
- predicate
Function: Function to test condition.
Returns
Function: Higher-order component.
# pure
Given a component returns the enhanced component augmented with a component only rerendering when its props/state change
Parameters
- mapComponentToEnhancedComponent
Function: Function mapping component to enhanced component. - modifierName
string: Seed name from which to generated display name.
Returns
WPComponent: Component class with generated display name assigned.
# useMediaQuery
Runs a media query and returns its value when it changes.
Parameters
- query
[string]: Media Query.
Returns
boolean: return value of the media query.
# useReducedMotion
Hook returning whether the user has a preference for reduced motion.
Returns
boolean: Reduced motion preference value.
# useViewportMatch
Returns true if the viewport matches the given query, or false otherwise.
Usage
useViewportMatch( 'huge', <' );
useViewportMatch( 'medium' );Parameters
- breakpoint
WPBreakpoint: Breakpoint size name. - operator
[WPViewportOperator]: Viewport operator.
Returns
boolean: Whether viewport matches query.
# withGlobalEvents
Higher-order component creator which, given an object of DOM event types and values corresponding to a callback function name on the component, will create or update a window event handler to invoke the callback when an event occurs. On behalf of the consuming developer, the higher-order component manages unbinding when the component unmounts, and binding at most a single event handler for the entire application.
Parameters
- eventTypesToHandlers
Object<string,string>: Object with keys of DOM event type, the value a name of the function on the original component's instance which handles the event.
Returns
Function: Higher-order component.
# withInstanceId
A Higher Order Component used to be provide a unique instance ID by component.
Parameters
- WrappedComponent
WPComponent: The wrapped component.
Returns
WPComponent: Component with an instanceId prop.
# withSafeTimeout
A higher-order component used to provide and manage delayed function calls that ought to be bound to a component's lifecycle.
Parameters
- OriginalComponent
WPComponent: Component requiring setTimeout
Returns
WPComponent: Wrapped component.
# withState
A Higher Order Component used to provide and manage internal component state via props.
Parameters
- initialState
?Object: Optional initial state of the component.
Returns
WPComponent: Wrapped component.
