rx-with-event-handler-props

rxjs-based component behaviour (reactive props stream operator) for lifting a component-from-stream that adds an event-handler property and injects an event property when that handler is called with a payload.

API

for a detailed specification of this API, run the unit tests in your browser.

example usage

const behaviour = compose(
  // ... behaviours that may depend on the injected { id: 'click' } EventProp
  withEventHandler('click'),
  // ... other behaviours that do not require access to the EventHandlerProps
)
// SFC that uses the handler from the EventHandlerProp
const Clickable = ({ onClick /*, other props */ }) => (
  <div onClick={onClick}>
  <!-- ... -->
  </div>
)
// ...
export componentFromStream(Clickable, behaviour)

by default, when the handler from the EventHanderProp is called, its payload is mapped to an EventProp property on the object emitted by the output stream:

(payload: E, id: string) => ({ event: { id, payload } })

alternatively, withEventHandler may be called with a custom event-to-event-prop mapping function that maps the handler's payload to a custom property on the output object. this may be used for example to generate an 'action' property instead of EventProp:

const createAction = type => payload => ({ action: { type, payload } })
const behaviour = compose(
  // ... behaviours that handle the 'action' property, e.g. with reducers
  withEventHandler(createAction('INCREMENT'))('click')
  // ...
)
// ...

type definitions

declare function withEventHandlerProps <E>(
  id: string
): EventHandlerPropsOperator<E>
declare function withEventHandlerProps <E>(
  /* project = (payload: E, id: string) => ({ event: { id, payload } }) */
): (id: string) => EventHandlerPropsOperator<E>
declare function withEventHandlerProps <E,L>(
  project: EventMapper<E,L>
): (id: string) => EventHandlerPropsOperator<E,L>

declare function hasEventHandler(id: string): (p: any) => boolean
declare function toHandlerKey (id: string): string
declare function hasEvent(id: string): (p: any) => boolean

type EventHandlerPropsOperator<E,L=EventProp<E>> =
<P>(props$: Observable<P>) => Observable<P&EventHandlerProps<E,L>>

type EventHandlerProps<E,L> = EventHandlerProp<E> & Partial<L>

interface EventHandlerProp<E> {
  [onId: string]: (event: E) => void
}

interface EventProp<E> {
  event: { id: string, payload: E|P, event?: E } // event? from Inferno LinkEvent
}

interface EventMapper<E,L=EventProp<E>> {
  (event: E, id?: string): L
  <P>(payload: P, event: E, id?: string): L // Inferno LinkEvent signature
}

in addition to the withEventHandlerProps default export, this module also exports three utility functions: hasEventHandler, hasEvent and toHandlerKey. the latter returns the props key of the handler function.

TypeScript

although this library is written in TypeScript, it may also be imported into plain JavaScript code: modern code editors will still benefit from the available type definition, e.g. for helpful code completion.

License

Copyright 2018 Stéphane M. Catala

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and Limitations under the License.