I'm bit of a novice to JavaScript so I've been wondering on positive and negative sides of using polling compared to using events in JavaScript? When does one use one or the other?
By polling I consider any effect that is triggered on something that repeats itself usually using setTimeout. But also for example:
function render() {
Bloop.renderComponent(box, document.body);
requestAnimationFrame(render);
}
Is also polling since requestAnimationFrame(render) which is called before each frame is called.
Basically anything that fits this definition
Best Answer
This is a bit of a "which is better, fish or the colour orange" type of question, but in terms of the general behaviour of JavaScript, and particularly the more functional side of it's nature it is probably more idiomatic to use events to react to changes of state than it is to have a timed polling system.
It is a lot more flexible and less confusing to be adding and removing event listeners as your application starts to grow. Polling is easier to conceptualise when you are first imagining everything clocking in to a central location, but as your application gets more complex that is liable to get increasingly difficult to do, whereas events can come from anywhere and go to anywhere so they are much less tightly coupled.
Also when an event is triggered and there is nobody to hear it, nothing happens. If you have a whole lot of timeout based polling loops, you may find that things are happening after the main system crashed as timeouts trigger, which makes debugging the problem or following up any logs more confusing.
Practically if you are animating things, you will probably want to use some degree of polling for your animation loop and events to communicate when to trigger other animations or when interactions occur, so you're likely to want to use both.