Enemy Shots Using Operators and Observables

We should allow the enemies in the game to shoot as well, Otherwise, it will be an unfair universe that we’ll have created, and a boring one! To enable enemy shots, we’ll do the following:

• Each enemy will keep an updated array of its own shots.
• Each enemy will shoot at a given frequency.

For this, we’ll use an interval operator to store new shots in the enemy value. We’ll also introduce a new helper function, isVisible, that helps filter out elements whose coordinates are outside the visible screen. This is how the Enemy Observable looks now: