closure concept usage in react hooks context.

jsClosure.js

function Func() {
  let a = 0;

  const callback = (a) => () => console.log(a);

  setTimeout(callback(a), 1000);

  a += 1;
  console.log(a);
}

Func();
/*
the nature of closure is to keep knowledge of what the closed-over values
 were when the closure was created - called "capturing".

react useEffect(callback, dependencies) hook behave like this!
the values that callback is closed-over are a list of component's state and props.

check this: https://reacttraining.com/blog/useEffect-is-not-the-new-componentDidMount/


*/

useEffectVScomponentDidMount.MD

"The difference is that useEffect captures the value of count when the effect gets created." notice to the difference of current value and captured value.

captured value of the value (state)

setValue(value+1)

current value of the value (state)

setValue(value=>value+1)