Event listeners acting as infinite loop
When we add an event listener, the thing is even though it's only a single line and not within an infinite loop, it works like it is within an infinite loop though, because it keeps track of the event every time. Can someone explain what happens internally when we add an event listener please
9 Replies
it's not acting like an infinite loop at all.
addEventListener registers the callback you pass it to be fired whenever the event triggers. The javascript engine then calls the callback whenever the event occursHmm the thing is when we register the event, is there some kind of loops which continously check if the event has been fired? How does the browser know that a particular event has been fired?
there's a bunch of ways that can work in the background. At the hardware level, it triggers an interrupt with can trigger code without needing a constant loop. I have no clue how it's actually implemented in the browser and javascript engine though. You really don't need to worry about the internals of the engine though
Ok, I will not worry about that for now then, thanks !
depend on the event, but you shouldnt have to even think about it
unless you are trying to do something super super super outside the "norm" and what you should do
by the way, some events will be more important than other events, and will execute before or even interrupt execution of other events
ya it's just a browse thing, u don't really need to worry about it
i assume the browser has a separate system where it keeps track of the events as they occur then simply checks if there's anything to be done upon that event being triggered, if so then ig the event handler handles that event , pushes the callback to the callstack
this is just my assumption , that could be how the whole thing is working
but yah there's really no reason to worry about these for the most part
they are thrown into the execution queue as they arrive, sorted by priority
ooh ya, i forgot that's a thing
Traversy Media has a great playlist on JavaScript Under the hood. i watched it long ago. pretty cool to know
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it is pretty cool how js does the single-threat thing