An implementation of WHATWG EventTarget interface, plus few extensions.
- This provides
EventTarget
constructor that can inherit for your custom object. - This provides an utility that defines properties of attribute listeners (e.g.
obj.onclick
).
// The prototype of this class has getters and setters of `onmessage` and `onerror`.
class Foo extends EventTarget("message", "error") {
//...
}
npm install --save event-target-shim
Or download from dist
directory.
//-----------------------------------------------------------------------------
// import (with browserify, webpack, etc...).
const EventTarget = require("event-target-shim");
//-----------------------------------------------------------------------------
// define a custom type.
class Foo extends EventTarget {
}
//-----------------------------------------------------------------------------
// add event listeners.
let foo = new Foo();
foo.addEventListener("foo", event => {
console.log(event.hello);
});
foo.addEventListener("foo", event => {
if (event.hello !== "hello") {
// event implements Event interface.
event.preventDefault();
}
});
//-----------------------------------------------------------------------------
// dispatch an event.
let event = document.createEvent("CustomEvent");
event.initCustomEvent("foo", /*bubbles*/ false, /*cancelable*/ false, /*detail*/ null);
event.hello = "hello";
foo.dispatchEvent(event);
//-----------------------------------------------------------------------------
// dispatch an event simply (non standard).
foo.dispatchEvent({type: "foo", hello: "hello"});
//-----------------------------------------------------------------------------
// dispatch a cancelable event.
if (!foo.dispatchEvent({type: "foo", cancelable: true, hello: "hey"})) {
console.log("defaultPrevented");
}
//-----------------------------------------------------------------------------
// If `window.EventTarget` exists, `EventTarget` inherits from `window.EventTarget`.
if (foo instanceof window.EventTarget) {
console.log("yay!");
}
//-----------------------------------------------------------------------------
// import (with browserify, webpack, etc...).
const EventTarget = require("event-target-shim");
//-----------------------------------------------------------------------------
// define a custom type with attribute listeners.
class Foo extends EventTarget("message", "error") {
}
// or non-variadic
class Foo extends EventTarget(["message", "error"]) {
}
//-----------------------------------------------------------------------------
// add event listeners.
let foo = new Foo();
foo.onmessage = event => {
console.log(event.data);
};
foo.onerror = event => {
console.log(event.message);
};
foo.addEventListener("message", event => {
console.log(event.data);
});
//-----------------------------------------------------------------------------
// dispatch a event simply (non standard).
foo.dispatchEvent({type: "message", data: "hello"});
foo.dispatchEvent({type: "error", message: "an error"});
-
Basic.
function Foo() { EventTarget.call(this); } Foo.prototype = Object.create(EventTarget.prototype, { constructor: { value: Foo, configurable: true, writable: true }, //.... });
-
With attribute listeners.
function Foo() { EventTarget.call(this); } Foo.prototype = Object.create(EventTarget("message", "error").prototype, { // or // Foo.prototype = Object.create(EventTarget(["message", "error"]).prototype, { constructor: { value: Foo, configurable: true, writable: true }, //.... });
require(["https://cdn.rawgit.com/mysticatea/event-target-shim/v2.0.0/dist/event-target-shim.min.js"], function(EventTarget) {
//...
});
declare class EventTarget {
constructor();
addEventListener(type: string, listener?: (event: Event) => void, options?: boolean | AddEventListenerOptions): void;
removeEventListener(type: string, listener?: (event: Event) => void, options?: boolean | EventListenerOptions): void;
dispatchEvent(event: Event | EventLike): boolean;
}
// Define EventTarget type with attribute listeners.
declare function EventTarget(...types: string[]): EventTarget;
declare function EventTarget(types: string[]): EventTarget;
// Options
interface EventListenerOptions {
capture?: boolean;
}
interface AddEventListenerOptions extends EventListenerOptions {
once?: boolean;
passive?: boolean;
}
// Non-standard.
interface EventLike {
type: string;
cancelable?: boolean;
}