emitter Function

Creates and returns a new Emitter instance in a convenient way that provides functionality to create streams, handle subscriptions, emit values to subscribers, and integrate with other reactive sources such as emitters, states, subjects, observables.

You can optionally provide an onInit callback that will be invoked just before the emitter’s initialization, allowing you to perform setup tasks or configure the emitter before it starts emitting values

@template T
The type of data emitted by this emitter

@param onInit?: (emitter: Emitter<T>) => void
An optional callback function that is called with the newly created Emitter instance just before its initialization. This function can be used to set up or configure the emitter

@returns Emitter<T>

API


function emitter<T>(onInit?: (emitter: Emitter<T>) => void): Emitter<T>;

Example


import {emitter, namedGroup} from '@bitfiber/rx';
import {take, filter, switchMap} from 'rxjs';
 
// Creates an emitter that emits the IDs
const currentId = emitter<number>(e => e
  // Transmits all emitted data to the 'productReq' emitter
  .transmit(productReq));
 
// The observable of the emitter
const currentId$ = currentId.$;
 
// Creates an emitter that emits the final ID
const lastId = emitter<number>();
 
// Creates an emitter that receives transmitted 'currentId' data and performs an effect that calls an API
const productReq = emitter<number>(e => e
  // All streams created by this emitter will filter the data
  .manage(
    filter(id => !!(id % 2)),
  )
  // Performs a tap callback each time the emitter emits new filtered data
  .tap(id => {
    console.log(id);
  })
  // Performs an effect each time the emitter emits new filtered data
  .effect(
    switchMap(id => productsService.get(`api/product${id}`)),
  ));
 
// Creates an emitter that receives used IDs and logs them through an effect
const log = emitter<string>(e => e
  // Runs an effect when data is received from the `currentId` emitter
  .receive(currentId, id => `A new id ${id} was received`)
  // Runs an effect when data is received from the `lastId` emitter
  .receive(lastId, id => `the last id ${id} was received`)
  // Performs an effect each time the emitter emits newly received logged data
  .effect(
    switchMap(log => logService.post(`api/log`, {log})),
  ));
 
// Creates an emitter that performs a tap callback each time data is selected
const result1 = emitter<[number, number]>(e => e
  // Runs a tap callback when all data is selected from the `currentId` and `lastId` emitters
  .select(currentId$, lastId, (currentId, lastId) => [currentId, lastId])
  // Performs a tap callback each time the emitter emits new data
  .tap(range => {
    console.log(range);
  }));
 
// Creates an emitter that performs a tap callback each time data is zipped
const result2 = emitter<[number, number]>(e => e
  // Runs a tap callback when all data is zipped from the `currentId` and `lastId` emitters
  .zip(currentId$, lastId, (currentId, lastId) => [currentId, lastId])
  // Performs a tap callback each time the emitter emits new data
  .tap(range => {
    console.log(range);
  }));
 
// Creates an emitter that emits the timestamp of the last received ID
const lastIdTime = emitter<number>(e => e
  // Waits for the first value from the `lastId` emitter, then completes the stream
  .wait(lastId, lastId => new Date().getTime()));
 
// Groups all emitters and states for mass initialization and completion
const group = namedGroup({currentId, lastId, productReq, log, result1, result2});
 
// Subscribe to the observable of the emitter
currentId$
  .pipe(take(1))
  .subscribe(id => {
    console.log(id);
  });
 
// Initializes the group and all items within the group
group.initialize();
 
// Emits data
currentId.emit(1);
currentId.emit(2);
 
// Accesses the 'lastId' emitter through the group
group.lastId.emit(3);
 
// Completes the group and all items within the group
group.complete();