proppy

Functional props composition for components

• Guide
  • Installation
  • Usage
    • Single functions
    • Composition
    • Providers
    • Subscription
• API
  • withProps
  • withState
  • compose
  • withReducer
  • withHandlers
  • withStateHandlers
  • withObservable
  • withTimer
  • onChange
  • map
  • shouldUpdate
  • didSubscribe
  • willDestroy
  • emit
  • handleReceivedProps
  • create

---

Guide

Installation

With npm:

$ npm install --save proppy

Via unpkg CDN:

<script src="https://unpkg.com/proppy@latest/dist/proppy.min.js"></script>
 
<script>
  // available as `window.Proppy`
</script> 

Usage

Single functions

Let's first import a function of our choice:

import { withState } from 'proppy';

Now we can create our factory:

const P = withState('counter', 'setCounter', 0);

The factory function can now be called to get the instance:

const p = P();

Accessing props:

console.log(p.props);
// { counter: 0, setCounter: Function }
 
p.props.setCounter(5);
 
console.log(p.props.counter);
// 5

Destroying the instance:

p.destroy();

Composition

You can also compose multiple factories together using the compose function:

import { compose, withProps, withState } from 'proppy';
 
const P = compose(
  withProps({ foo: 'foo value' }),
  withState('counter', 'setCounter', 0),
  withState('age', 'setAge', 20),
);

You can now get your instance by calling the returned function:

const p = P();
 
console.log(p.props);
// {
//   foo: 'foo value',
//
//   counter: 0,
//   setCounter: Function,
//
//   age: 20,
//   setAge: Function
// }

Providers

Providers are values which are made accessible to instances.

When we call our factory function to get the instance, we can optionally pass an object that will contain all our providers:

import { compose, withProps } from 'proppy';
 
const P = compose(
  // value already known
  withprops({
    foo: 'foo value',
  }),
 
  // value will be obtained from providers
  withProps((props, providers) => ({
    // `props` is `{ foo: 'foo value' }` here
    bar: providers.bar,
  }),
);

Now we can pass the providers object when calling P:

const p = P({
  bar: 'bar value',
});
 
console.log(p.props);
// {
//   foo: 'foo value',
//   bar: 'bar value',
// }

Subscription

Subscribing to props changes:

const unsubscribe = p.subscribe(props => console.log(props));

To Unsubscribe:

unsubscribe();

API

withProps

withProps(props)

withProps((currentProps, providers) => props)

Used for generating initial props.

Examples:

Directly passing the props object:

const P = withProps({ foo: 'foo value' });

Returning the props from a function:

const P = withProps((currentProps, providers) => {
  return {
    foo: 'foo value'
  };
});

withState

withState(stateName, setterName, initialState)

Used for state management.

Examples:

const P = withState('counter', 'setCounter', 0);

compose

compose(...factories)

Used for composing multiple factories into a single one.

Examples:

const P = compose(
  withProps({ foo: 'foo value '}),
  withprops({ bar: 'bar value' }),
  withState('counter', 'setCounter', 0),
);

withReducer

withReducer(stateName, dispatcherNAme, reducer, initialState)

For generating props via reducer functions.

Arguments:

1. stateName (String): Name of the prop where state will be set
2. dispatcherName (String): Name of the prop for setting dispatch function
3. reducer (Function): Accepting (state, action), and returning new state
4. initialState (Any): Initial state to begin with

Example:

function reducer(state, action) {
  switch (action.type) {
    case 'INCREMENT':
      return { value: state.value + 1 };
    case 'DECREMENT':
      return { value: state.value - 1 };
    default:
      return state;
  }
}
 
const P = withReducer('counter', 'dispatch', reducer, { value: 0 });
const p = P();
 
p.dispatch({ type: 'INCREMENT' });
console.log(p.props.counter) // { value: 1 }

You can also pass functions to dispatch:

p.dispatch(function (props, providers) {
  return { type: 'INCREMENT' };
});

withHandlers

withHandlers(handlers)

Used for handling side-effects.

Examples:

Basic handler:

const P = withHandlers({
  handleFoo: (props, providers) => () => console.log('handling foo!')
});

A better example with composition:

const P = compose(
  withState('counter', 'setCounter', 0),
  withHandlers({
    incrementBy: (props, providers) => (n) => {
      props.setCounter(props.counter + n);
    },
  }),
);
 
const p = P();
 
p.incrementBy(1);
console.log(p.props.counter); // 1

withStateHandlers

withStateHandlers(initialState, handlers)

Used for state management via handlers.

Examples:

const P = withStateHandlers(
  // initial state
  {
    counter: 0,
  },
 
  // handlers
  {
    incrementBy: (props, providers) => (n) => {
      // return new state
      return {
        counter: props.counter + n,
      };
    }
  }
);
 
const p = P();
p.incrementBy(5);
p.incrementBy(5);
console.log(p.props.counter); // 10

withObservable

withObservable((props, providers) => props$)

Used for returning an Observable of props.

Examples:

import { of } from 'rxjs';
 
const P = withObservable((props, providers) => {
  return of({
    foo: 'foo value',
  });
});

For advanced usage, look into proppy-rx package, where you can also access incoming props as an Observable.

withTimer

withTimer(timer, props)

withTimer(timer, (props, providers) => props)

Sets props after timer has elapsed.

Examples:

// prop `foo` is set after 1 second
const P = withTimer(1000, { foo: 'foo value' });

Accessing current props and providers:

const P = withTimer(100, (props, providers) => ({
  foo: 'foo value',
}));

onChange

onChange(propName, (prop, providers) => props)

onChange( (prevProps, nextProps) => true, (props, providers) => props )

onChange( propName, (props, providers, cb) => void )

Detect a change in props, and return new props.

Examples:

Change foo, when counter changes:

const P = compose(
  withProps({ foo: 'initial foo value' })
  withState('counter', 'setCounter', 0),
  onChange('counter', (props, providers) => ({
    foo: `changed foo with counter ${props.counter}`
  }))
);
 
const p = P();
console.log(p.props.foo); // `initial foo value`
 
p.props.setCounter(10);
console.log(p.props.foo); // `changed foo with counter 10`

Detecting complex changes:

const P = compose(
  withState('counter', 'setCounter', 0),
  onChange(
    // detect
    (prevProps, nextProps) => true,
 
    // return props
    (props, providers) => props
  )
);

Returning async props:

const P = compose(
  withState('counter', 'setCounter', 0),
  onChange(
    // detect
    (prevProps, nextProps) => true,
 
    // return props by callback
    (props, providers, cb) => {
      cb(props);
    }
  )
);

map

map((props, providers) => props)

Used for mapping incoming props to returned props.

Examples:

const P = compose(
  withProps({ foo: 'foo value' }),
  map(props => ({ foo: props.foo.toUpperCase() })),
);

shouldUpdate

shouldUpdate((prevProps, nextProps, providers) => true)

Used for limiting the events

Examples:

const P = compose(
  withState('counter', 'setCounter', 0),
  shouldUpdate((prevProps, nextProps) => {
    // emit further only if counter is an even number
    return nextProps.counter % 2 === 0;
  });
);

didSubscribe

didSubscribe((props, providers) => {})

For handling side-effects upon first subscription.

Examples:

const P = didSubscribe((props, providers) => {
  // do something
 
  // optionally return a function
  // that will be called when instance is destroyed
  return () => {};
})

willDestroy

willDestroy((props, providers) => {})

For handling side-effects when instance is destroyed.

emit

emit((cb, props, providers) => {})

For emitting new props after subscription.

Examples:

const P = emit((cb, props, providers) => {
  cb({ foo: 'foo value' });
 
  // optionally return a function
  // that will be called when instance is destroyed
  return () => {};
});

handleReceivedProps

handleReceivedProps(true|false)

handleReceivedProps((receivedProps) => {})

Accept props coming from parent instances.

create

create(options)

Convenience function for creating your own functions, that can return factories.

All the other functions in this library are built by using this create function internally.

Arguments:

• options.initialize (Function)
• options.didSubscribe (Function)
• options.willDestroy (Function)
• options.handleReceivedProps (Boolean|Function)

Examples:

A producer of props:

function withFoo() {
  return create({
    initialize() {
      // has access to:
      //   - this.props
      //   - this.providers
 
      this.set({
        foo: 'foo value',
      });
    }
  });
}

A mapper of props:

function capitalizeFoo() {
  return create({
    handleReceivedProps(receivedProps) {
      this.set({
        ...receivedProps,
        foo: typeof receivedProps.foo !== 'undefined'
          ? receivedProps.foo.toUpperCase()
          : undefined,
      })
    }
  });
}