EVT
v2
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Evt.from<T>(...)

Creates an Evt that post events of a specific type coming from other API that emmits events.

Returns

Evt<T> will post every time the emitter emits

Parameters

Ctx Optional, Allows detaching the handlers attached to the source emitter.
emitter: Any of the following,
  • DOM EventTarget
  • ​ResizeObserver​
  • Node.js EventEmitter
  • JQuery-like event target
  • RxJS Subject
  • An Array, NodeList or HTMLCollection of many of these.
  • A promise
Depending of the API the type argument will be inferred or not.
name: The event name of interest, being emitted by the target.

Examples

With DOM EventTarget

import { Evt } from "evt";
​
Evt.from(document, "click").attach(mouseEvent=> {/*...*/});
​
const ctx = Evt.newCtx();
​
Evt.from(ctx, document, "wheel").attach(wheelEvent=> {/*...*/});
​Run the example​
declare const htmlButtonElement: HTMLButtonElement;
​
Evt.from(ctx, htmlButtonElement, "click").attach(mouseEvent => {/* ... */});
​Run the example​

From ResizeObserver​

const ctx = Evt.createCtx();
declare const htmlDivElement: HTMLDivElement;
​
Evt.from(ctx, ResizeObserver, htmlDivElement).attach(resizeObserverEntry=>{/* ... */});

From EventEmitter

import { Evt } from "evt";
import { EventEmitter } from "events";
​
const ctx= Evt.newCtx();
​
const ee= new EventEmitter();
const evtText= Evt.from<string>(ctx, ee, "text");
evtText.attach(text=> console.log(text));
​
evtText.post("Foo bar");//Prints "Foo bar";
​
ctx.done();
​
console.log(ee.listenerCount("text"));//Prints "0"
​Run the example​

With RxJS Subject

import { Evt } from "evt";
import { Subject } from "rxjs";
​
const ctx= Evt.newCtx();
​
const subject = new Subject<string>();
​
const evtText = Evt.from(ctx, subject); //The type argument is inferred.
​
evtText.attach(text=> console.log(text));
​
subject.next("Foo bar"); //Prints "Foo bar"
​
ctx.done();
​
subject.next("Foo bar"); //Prints nothing
​Run the example​

With JQuery-like event target

import { Evt } from "evt";
​
Evt.from([
$("#btnA"),
$("#btnB"),
$("#btnC")
], "click").attach(()=> console.log("Clicked!"));