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NPM CircleCI License

reactive-properties

A lightweight alternative for RX and Redux, that utilises react hooks and dramatically reduces the amount of boiler plate code for the typical React application.

Installation

npm install --save reactive-properties
yarn add reactive-properties

Documetation

Property

interface Property<T> {
  
  get(): T // returns the current value

  subscribe(callback: () => void): () => void // subscribe to future values

}

Property is just a variable that can be observed.

To get the current value use the get method. To subscribe to future updates, use the subscribe method. Subscribe returns a function which can be called to unsubscribe from updates.

Piping

For developer convenience all properties have a pipe method. It can be used to apply operators to a property.

property.pipe(
  withEffect(() => { ... }),
  map(x => x * 2),
)

State

Simplest property implementation. You provide the default value and can call the set method to update the value.

const state = new State(5)

console.log(state.get()) // prints 5

state.set(42)

console.log(state.get()) // prints 42

state.subscribe(() => console.log('Update:', state.get()))

state.set(99) // "Update: 99" is printed to the console

Sends update notifications to all subscribers when the new value is set.

combine

Used to combine multiple properties into one.

const a = new State(2)
const b = new State(2)

const sum = combine([a, b], (a, b) => a + b) // sum is 4

b.set(5) // sum is now 7

a.set(6) // sum is now 11

Updates every time when one of the source properties update.

map operator

Works similarly to Array.map. Creates a new property which will always have values that are obtained by mapping the original property's values with the provided function.

withEffect operator

Provides a way to add custom imperative logic when something starts observing the property.

property.pipe(
  withEffect(() => {
    console.log('Property started to be observed')

    return () => console.log('All observers unsubscribed')
  })
)

Works similarly to React's useEffect. Can be usefull to start and stop background tasks when user visits a specific page, for example.

forEach operator

Calls provided callback for each value that a property has. Including the current one.

waitFor operator

Converts the property to a promise that resolves when the provided predicate returns true. Promise resolves with the first value that matched the predicate.

dedupBy operator

Stops updates when property values don't change. Example:

const state = new State(0)

state.forEach(console.log) // prints 0

state.set(0) // nothing printed

state.set(1) // prints 1

state.set(1) // nothing printed

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Simple reactive property system

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