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


Evt<T> will post every time the emitter emits


Ctx Optional, Allows detaching the handlers attached to the source emitter.

emitter: Any of the following,

  • DOM EventTarget

  • 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.


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

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";


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"


subject.next("Foo bar"); //Prints nothing

Run the example

With JQuery-like event target

import { Evt } from "evt";

], "click").attach(()=> console.log("Clicked!"));

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