Add TypeScript definition and examples

Fixes #13. Closes #17.

.gitignore

@@ -3,3 +3,4 @@ yarn.lock
 .nyc_output
 coverage
 /legacy.js
+/legacy.d.ts

examples/.gitignore

@@ -0,0 +1 @@
+/clocktyped.js

examples/clock.js

@@ -0,0 +1,79 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const Emittery = require('../');
+
+class Clock extends Emittery {
+
+	constructor(tick = 1000) {
+		super();
+
+		this._startedAt = 0;
+		this._tick = tick > 0 ? tick : 1000;
+		this._timer = null;
+	}
+
+	async tick() {
+		if (this._timer === null) {
+			await this.emit('error', new Error('not started'));
+			this.stop();
+			return;
+		}
+
+		const now = Date.now();
+		const duration = now - this._startedAt;
+
+		return this.emit('tick', {now, duration});
+	}
+
+	start() {
+		this._startedAt = Date.now();
+		this._timer = setInterval(this.tick.bind(this), this._tick);
+		this.emit('started', null);
+	}
+
+	stop() {
+		if (this._timer !== null) {
+			clearInterval(this._timer);
+		}
+
+		this._timer = null;
+		this._startedAt = 0;
+		this.emit('stopped', null);
+	}
+}
+
+const timer = new Clock();
+const offTick = timer.on('tick', onTick);
+const offError = timer.on('error', onError);
+
+timer.start();
+
+function onTick({duration}) {
+	console.log(Math.floor(duration / 1000));
+
+	if (duration > 5999) {
+		stop();
+	}
+}
+
+function onError(err) {
+	stop();
+	console.error(err);
+	process.exit(1);
+}
+
+function stop() {
+	offTick();
+	offError();
+	timer.stop();
+}
+
+// Prints:
+// 		1
+// 		2
+// 		3
+// 		4
+// 		5
+// 		6

examples/clocktyped.ts

@@ -0,0 +1,99 @@
+#!/usr/bin/env ts-node
+import _Emittery = require('../');
+
+// Alias Emittery class to use mapped event types
+const Emittery = _Emittery as _Emittery.MappedCtor;
+
+interface TickData {
+	now: number;
+	duration: number;
+}
+
+// Map Clock's events emitting data to the type of their data.
+type EventDataMap = {
+	tick: TickData,
+	error: Error
+};
+
+// List of event which do not required data
+type EmptyEvents = 'started' | 'stopped';
+
+class Clock extends Emittery<EventDataMap, EmptyEvents> {
+
+	private _tick: number;
+	private _timer: NodeJS.Timer | null;
+	private _startedAt = 0;
+
+	constructor(tick = 1000) {
+		super();
+
+		this._tick = tick > 0 ? tick : 1000;
+		this._timer = null;
+	}
+
+	async tick(): Promise<void> {
+		if (this._timer == null) {
+			await this.emit('error', new Error('not started'));
+			this.stop();
+			return;
+		}
+
+		const now = Date.now();
+		const duration = now - this._startedAt;
+
+		return this.emit('tick', {now, duration});
+	}
+
+	start() {
+		this._startedAt = Date.now();
+		this._timer = setInterval(this.tick.bind(this), this._tick);
+
+		this.emit('started');
+	}
+
+	stop() {
+		if (this._timer != null) {
+			clearInterval(this._timer);
+		}
+
+		this._timer = null;
+		this._startedAt = 0;
+
+		this.emit('stopped');
+	}
+
+}
+
+const timer = new Clock();
+const offTick = timer.on('tick', onTick);
+const offError = timer.on('error', onError);
+
+timer.start();
+
+function onTick({duration}: TickData) {
+	console.log(Math.floor(duration/1000));
+
+	if (duration > 5999) {
+		stop();
+	}
+}
+
+function onError(err: Error) {
+	stop();
+	console.error(err);
+	process.exit(1);
+}
+
+function stop() {
+	offTick();
+	offError();
+	timer.stop();
+}
+
+// Prints:
+// 		1
+// 		2
+// 		3
+// 		4
+// 		5
+// 		6

examples/emit.js

@@ -0,0 +1,18 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const Emittery = require('../');
+
+const myEmitter = new Emittery();
+
+// Emit event in next tick
+myEmitter.emit('event');
+
+// Register listener
+myEmitter.on('event', () => console.log('an event occurred!'));
+myEmitter.onAny(eventName => console.log('"%s" event occurred!', eventName));
+
+// Prints:
+// 		an event occurred!
+// 		"event" event occurred!

examples/emitonce.js

@@ -0,0 +1,20 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const Emittery = require('../');
+
+class MyEmitter extends Emittery {}
+
+const myEmitter = new MyEmitter();
+
+// Emit events in next tick
+myEmitter.emit('event', 1);
+myEmitter.emit('event', 2);
+
+// Register listener for only the one event
+myEmitter.once('event')
+	.then(count => console.log('an event occurred (#%d).', count));
+
+// Prints:
+//		an event occurred (#1).

examples/eventdata.js

@@ -0,0 +1,20 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const Emittery = require('../');
+
+class MyEmitter extends Emittery {}
+
+const myEmitter = new MyEmitter();
+
+// Only accept one event data parameter
+myEmitter.emit('event', {a: true, b: true}, 'not', 'supported');
+
+// Does not provide a context either.
+myEmitter.on('event', function ({a, b}, ...args) {
+	console.log(a, b, args, this);
+});
+
+// Prints:
+// 		true true [] undefined