TypeScript decorator to apply to a method that should only be invoked in response to certain keypress events.

key-listener.ts

export const enum KeyCode {
	ENTER = 13,
	SPACE = 32
}

export function keyListener(keyCodes: KeyCode | KeyCode[]) {
	if (!(keyCodes instanceof Array)) {
		keyCodes = [keyCodes];
	}

	return (_target: any, _key: string, descriptor: PropertyDescriptor) => {
		const decorated: Function = descriptor.value;
		descriptor.value = function(event: KeyboardEvent) {
			if (!event || !(event instanceof KeyboardEvent) || !(<number[]><any>keyCodes).includes(event.keyCode)) {
				return;
			}
			event.preventDefault();
			return decorated.apply(this, arguments);
		}
	}
}

usage.ts

import {keyListener, KeyCode} from "src/util/events";

class MyEventProcessor {

	@keyListener(KeyCode.ENTER)
	enterListener() {
		console.log(this, arguments);
	}

	@keyListener([KeyCode.ENTER, KeyCode.SPACE])
	multiListener() {
		console.log(this, arguments);
	}
}