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Module

x/enzastdlib/events/eventtarget.ts>TypedEventTarget

enzastdlib is a set of TypeScript modules that follow a common design API philosophy aiming at sane defaults and ease-of-use targeting the Deno TypeScript runtime.
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class TypedEventTarget
extends EventTarget
import { TypedEventTarget } from "https://deno.land/x/enzastdlib@v0.0.4/events/eventtarget.ts";

Represents a strongly-typed inheritable verison of the standard Web API EventTarget.

Examples

Example 1

import {
    assertEquals,
    assertInstanceOf,
} from 'https://deno.land/std/testing/asserts.ts';
import { TypedEventTarget } from 'https://deno.land/x/enzastdlib/events/mod.ts';

interface UpdateEventDetail {
    original: unknown;

    replacement: unknown;
}

class UpdateEvent extends CustomEvent<UpdateEventDetail> {
    constructor(detail: UpdateEventDetail) {
        // **IMPORTANT**: Make sure to set the name of your event in the
        // constructor to match the one located in your event record.
        //
        // Which in this case is `update`.
        super('update', { detail });
    }
}

type MyEvents = {
    update: UpdateEvent;
};

class MyEventTarget extends TypedEventTarget<MyEvents> {}

// **NOTE**: Alternatively you can just construct the `TypedEventTarget` without
// using inheritence:
//
// const event_target = new TypedEventTarget<MyEvents>();
const event_target = new MyEventTarget();

assertInstanceOf(event_target, EventTarget);

event_target.addEventListener('update', (event: UpdateEvent): void => {
    assertInstanceOf(event, CustomEvent);

    assertEquals(event.detail, {
        original: 42,
        replacement: 82,
    });
});

const event = new UpdateEvent({
    original: 42,
    replacement: 84,
});

event_target.dispatchEvent(event);

Methods

addEventListener<Type extends keyof EventRecord>(
type: Type,
listener: TypedEventListener<EventRecord[Type]> | null,
options?: boolean | AddEventListenerOptions | undefined,
): void

Appends an event listener for events whose type attribute value is type. The callback argument sets the callback that will be invoked when the event is dispatched.

The options argument sets listener-specific options. For compatibility this can be a boolean, in which case the method behaves exactly as if the value was specified as options's capture.

When set to true, options's capture prevents callback from being invoked when the event's eventPhase attribute value is BUBBLING_PHASE. When false (or not present), callback will not be invoked when event's eventPhase attribute value is CAPTURING_PHASE. Either way, callback will be invoked if event's eventPhase attribute value is AT_TARGET.

When set to true, options's passive indicates that the callback will not cancel the event by invoking preventDefault(). This is used to enable performance optimizations described in § 2.8 Observing event listeners.

When set to true, options's once indicates that the callback will only be invoked once after which the event listener will be removed.

The event listener is appended to target's event listener list and is not appended if it has the same type, callback, and capture.

dispatchEvent<Event extends EventRecord[keyof EventRecord]>(event: Event): boolean

Dispatches a synthetic event event to target and returns true if either event's cancelable attribute value is false or its preventDefault() method was not invoked, and false otherwise.

removeEventListener<Type extends keyof EventRecord>(
type: Type,
listener: TypedEventListener<EventRecord[Type]> | null,
options?: boolean | EventListenerOptions | undefined,
): void

Removes the event listener in target's event listener list with the same type, callback, and options.