split(trigger, cases)
Pattern matching method, splits trigger unit (event, effect or store) into several events, which fire upon trigger matches its comparator function.
Arguments
trigger
(Event | Effect | Store): Event, Effect or Store unit-trigger.cases
(Object): Schema of cases, which uses names of resulting events as keys, and comparator function((value) => Boolean)
Returns
(Object) - Object, having keys, defined in cases
argument, plus __
(two underscores) - which stands for default
(no matches met) case.
Example 1
import {createEvent, split} from 'effector'
const message = createEvent()
const messageByAuthor = split(message, { bob: ({user}) => user === 'bob', alice: ({user}) => user === 'alice',})messageByAuthor.bob.watch(({text}) => { console.log('[bob]: ', text)})messageByAuthor.alice.watch(({text}) => { console.log('[alice]: ', text)})
message({user: 'bob', text: 'Hello'})// => [bob]: Hellomessage({user: 'alice', text: 'Hi bob'})// => [alice]: Hi bob
/* default case, triggered if no one condition met */const {__: guest} = messageByAuthorguest.watch(({text}) => { console.log('[guest]: ', text)})message({user: 'unregistered', text: 'hi'})// => [guest]: hi
Note: the only first met match will trigger resulting event
Example 2
import {createEvent, split} from 'effector'
const message = createEvent()
const {short, long, medium} = split(message, { short: m => m.length <= 5, medium: m => m.length > 5 && m.length <= 10, long: m => m.length > 10,})
short.watch(m => console.log(`short message '${m}'`))medium.watch(m => console.log(`medium message '${m}'`))long.watch(m => console.log(`long message '${m}'`))
message('Hello, Bob!')// => long message 'Hello, Bob!'
message('Hi!')// => short message 'Hi!'