Read and write values to a state object and listen for changes at any given path
npm i state-eventer
// initialize an empty state
const state = new StateEventer()
state.get() // {}
// listen for state changes at specific paths
const listeners = [
state.on('books', console.log),
state.on('books.1', console.log)
]
// remove listener
listeners[0].off()
// add/modify value and notify listeners
state.set('books.1.title', 'War and Peace')
// retrieve values from the state
state.get() // { books: { 1: { title: 'War and Peace' } } }
state.get('books') // { 1: { title: 'War and Peace' } }
state.get('books.1') // { title: 'War and Peace' }
state.get('books.1.title') // 'War and Peace'
// remove values from the state and notify listeners
state.unset('books.1.title')
state.get('books.1.title') // undefined
// reset the entire state and notify listeners
state.set({})
state.get() // {}
// transform
state.update('counter', n => n + 1, 0) // 1
-
path
(String|Array) the path to listen for changes -
listenerFn
(Function) the function to call when the value changes
Returns Listener
(see below)
-
path
(String|Array) the path of the desired value -
defaultValue
(*) optional default value to return if the value at the specified path is undefined
-
path
(String|Array) the path at which to set the value -
value
the value to set
-
value
(Object) resets the root state to this value
-
path
(String|Array) removes this path from the state
-
path
(String|Array) the path at which to set the value -
transformFn
(Function) transform the current value to a new value -
defaultValue
(*) optional default value to pass into the transform function if the value at the given path is undefinedupdate('counter', n => n + 1, 0)
MIT