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EventTarget.ts
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EventTarget.ts
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import IEventListener from './IEventListener';
import Event from './Event';
import IEventTarget from './IEventTarget';
/**
* Handles events.
*/
export default abstract class EventTarget implements IEventTarget {
public readonly _listeners: {
[k: string]: (((event: Event) => void) | IEventListener)[];
} = {};
/**
* Adds an event listener.
*
* @param type Event type.
* @param listener Listener.
*/
public addEventListener(type: string, listener: ((event: Event) => void) | IEventListener): void {
this._listeners[type] = this._listeners[type] || [];
this._listeners[type].push(listener);
}
/**
* Adds an event listener.
*
* @param type Event type.
* @param listener Listener.
*/
public removeEventListener(
type: string,
listener: ((event: Event) => void) | IEventListener
): void {
if (this._listeners[type]) {
const index = this._listeners[type].indexOf(listener);
if (index !== -1) {
this._listeners[type].splice(index, 1);
}
}
}
/**
* Dispatches an event.
*
* @param event Event.
* @returns The return value is false if event is cancelable and at least one of the event handlers which handled this event called Event.preventDefault().
*/
public dispatchEvent(event: Event): boolean {
if (!event.target) {
event.target = this;
}
event.currentTarget = this;
const onEventName = 'on' + event.type.toLowerCase();
if (typeof this[onEventName] === 'function') {
this[onEventName].call(this, event);
}
if (this._listeners[event.type]) {
for (const listener of this._listeners[event.type]) {
if ((<IEventListener>listener).handleEvent) {
(<IEventListener>listener).handleEvent(event);
} else {
(<(event: Event) => void>listener).call(this, event);
}
if (event._immediatePropagationStopped) {
return !(event.cancelable && event.defaultPrevented);
}
}
}
return !(event.cancelable && event.defaultPrevented);
}
/**
* Adds an event listener.
*
* TODO:
* Was used by with IE8- and Opera. React believed Happy DOM was a legacy browser and used them, but that is no longer the case, so we should remove this method after that this is verified.
*
* @deprecated
* @param type Event type.
* @param listener Listener.
*/
public attachEvent(type: string, listener: ((event: Event) => void) | IEventListener): void {
this.addEventListener(type.replace('on', ''), listener);
}
/**
* Removes an event listener.
*
* TODO:
* Was used by IE8- and Opera. React believed Happy DOM was a legacy browser and used them, but that is no longer the case, so we should remove this method after that this is verified.
*
* @deprecated
* @param type Event type.
* @param listener Listener.
*/
public detachEvent(type: string, listener: ((event: Event) => void) | IEventListener): void {
this.removeEventListener(type.replace('on', ''), listener);
}
}