event-target-shim's Introduction

event-target-shim

A polyfill for W3C EventTarget, plus few extensions.

Overview

This module provides EventTarget constructor that is possible to inherit for your custom object.
This module provides an utility in order to define properties for attribute listeners (e.g. obj.onclick).

If window.EventTarget exists, EventTarget is inherit from window.EventTarget. In short, obj instanceof window.EventTarget === true.

declare class EventTarget {
  constructor();
  addEventListener(type: string, listener: (event: Event) => void, capture?: boolean): void;
  removeEventListener(type: string, listener: (event: Event) => void, capture?: boolean): void;
  dispatchEvent(event: Event): void;
}

// Define EventTarget type with attribute listeners.
declare function EventTarget(...types: string[]): typeof EventTarget;

Installation

npm install event-target-shim

Usage

import EventTarget from "event-target-shim";

class YourCoolType extends EventTarget {
  // ...
}

// This prototype has getters/setters of `onmessage` and `onerror`.
class YourAwesomeType extends EventTarget("message", "error") {
  // ...
}

I prefer use together with Browserify.

But we can use together with RequireJS, instead. In this case, please download a file from dist directory of repo.

define("MagicalBox", ["event-target-shim"], function (EventTarget) {
  function MagicalBox() {
    EventTarget.call(this);
  }

  MagicalBox.prototype = Object.create(EventTarget.prototype, {
    constructor: {
      value: MagicalBox,
      configurable: true,
      writable: true
    },

    // ...
  });

  return MagicalBox;
});

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