gistfile1.ts

class EventTargetMixin implements EventTarget {
	private listeners: { [kind: string]: EventListener[] } = { };

	addEventListener(type: string, listener: EventListener, useCapture = false) {
		this.listeners[type] = this.listeners[type] || [];
		if (useCapture) {
			this.listeners[type].unshift(listener);
		} else {
			this.listeners[type].push(listener);
		}
	}

	removeEventListener(type: string, listener: EventListener, useCapture = false) {
		if (this.listeners[type] === undefined) {
			return;
		}

		for (var i = 0; i < this.listeners[type].length; ++i) {
			if (this.listeners[type][i] === listener) {
				this.listeners[type].splice(i, 1);
				if (this.listeners[type].length === 0) {
					delete this.listeners[type];
				}
				return;
			}
		}
	}

	dispatchEvent(event: Event) {
		event.target = this;

		if (this.listeners[event.type] === undefined) {
			return;
		}

		var defaultPrevented = false;
		this.listeners[event.type].forEach((listener) => {
			listener(event);
			if (event.defaultPrevented) {
				defaultPrevented = true;
			}
		});
		
		return !defaultPrevented;
	}
}