Skip to main content
Module

x/enzastdlib/events/eventtarget.ts>TypedEventTarget#addEventListener

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.
Latest
method TypedEventTarget.prototype.addEventListener
import { TypedEventTarget } from "https://deno.land/x/enzastdlib@v0.0.4/events/eventtarget.ts";

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.

Examples

Example 1

import { TypedEventTarget } from 'https://deno.land/x/enzastdlib/events/mod.ts';

type MyEvents = {
    myEvent: CustomEvent<{ myValue: number }>;
};

const event_target = new TypedEventTarget<MyEvents>();

event_target.addEventListener(
    'myEvent',
    (event) => console.log(event.detail.myValue),
);

Type Parameters

Type extends keyof EventRecord

Parameters

type: Type
listener: TypedEventListener<EventRecord[Type]> | null
optional
options: boolean | AddEventListenerOptions | undefined