Most efficient way to detect a variable changed and execute a callback

Question

I would like to detect when a variable's value is updated on a server and run a callback that sends the new value to a client in order to provide a real-time feed. For example, say a server generates a random number at random intervals, but it's important for the client to be aware of a new number being generated as soon as it happens.

One simple solution is to define a custom function that you use to set your value instead of directly setting it with '=':

function setValue(val) { a = val; websocket.send(a) }

But that requires going back through already written code and replacing all instances of that variable being updated to instead use the custom function. A tedious and error-prone process but only has to be done once.

Another solution that I read about is to define a setter on the variable when initializing it, as described here . This would only require replacing all the places where the variable is being initialized for the first time, but since it's listening hidden in the background I worry it reduces readability and someone may forget there's a callback firing each time the variable is being updated.

I don't code professionally so I'm not sure which of these solutions would be more widely accepted, or if there's a better way I should be approaching it. Also not sure of the performance hit this would cause but I'm guessing pretty negligible.

Answer 1

Define the custom function. Take the refactor pain now and keep it readable. Coding is 20% creation and 80% maintenance, but it always feels like 99% creation and 1% maintenance when you're in the thick of making something new.