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=> {/*...*/});
declare const htmlButtonElement: HTMLButtonElement;
Evt.from(ctx, htmlButtonElement, "click").attach(mouseEvent => {/* ... */});
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));"Foo bar");//Prints "Foo bar";
console.log(ee.listenerCount("text"));//Prints "0"

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));"Foo bar"); //Prints "Foo bar"
ctx.done();"Foo bar"); //Prints nothing

With JQuery-like event target

import { Evt } from "evt";
], "click").attach(()=> console.log("Clicked!"));