Why use callback in JavaScript, what are its advantages?

Question

Could someone explain, why do we use callback in JavaScript? I found examples, but they could be implemented by using the normal functions. What is the advantage of using it

Answer 1

Is asynchronous programming akin to multi-threading?

Yes.

Javascript's asynch model provides a way to do work "in the background".

Suppose you have a long-running calculation. This might be hard to imagine for a simple js demo, but imagine a long decompression routine, or a long-running pathfinding algorithm in a game, etc. some numerical calculation that takes more than a second.

Doing the calculation by directly invoking the function will work, but it will suspend the browser UI for the duration of the calculation. Running things asynchronously means the browser UI remains responsive, as the calculation continues running on a background thread. When the calc completes, according to the asynch programming pattern, the function invokes the callback function, notifying the application layer that the calculation is complete.