Add types (#32)

* Add types

* Add return type and fix type

src/tinykeys.ts

@@ -103,15 +103,15 @@ function match(event: KeyboardEvent, press: KeyBindingPress): boolean {
 export default function keybindings(
 	target: Window | HTMLElement,
 	keyBindingMap: KeyBindingMap,
-) {
+): () => void {
 	let keyBindings = Object.keys(keyBindingMap).map(key => {
 		return [parse(key), keyBindingMap[key]] as const
 	})
 
 	let possibleMatches = new Map<KeyBindingPress[], KeyBindingPress[]>()
-	let timer: any = null
+	let timer: NodeJS.Timeout | null = null
 
-	let onKeyDown = (event: KeyboardEvent) => {
+	let onKeyDown: EventListener = event => {
 		// Ensure and stop any event that isn't a full keyboard event.
 		// Autocomplete option navigation and selection would fire a instanceof Event,
 		// instead of the expected KeyboardEvent
@@ -146,12 +146,16 @@ export default function keybindings(
 			}
 		})
 
-		clearTimeout(timer)
+		if (timer) {
+			clearTimeout(timer)
+		}
+
 		timer = setTimeout(possibleMatches.clear.bind(possibleMatches), TIMEOUT)
 	}
 
-	target.addEventListener("keydown", onKeyDown as any)
+	target.addEventListener("keydown", onKeyDown)
+
 	return () => {
-		target.removeEventListener("keydown", onKeyDown as any)
+		target.removeEventListener("keydown", onKeyDown)
 	}
 }