feat(hooks): add 'useIsMounted'

[sukvvon]

Overview

Checklist

• Did you write the test code?
• Have you run yarn run fix to format and lint the code and docs?
• Have you run yarn run test:coverage to make sure there is no uncovered line?
• Did you write the JSDoc?

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (bea638d) to head (49b5df8).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #244   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           33        34    +1     
  Lines          836       847   +11     
  Branches       254       258    +4     
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+ Hits           836       847   +11     

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[seungrodotlee]

According to our design principles, we might need to carefully consider whether providing this hook is the right approach.

[sukvvon]

@seungrodotlee

Thank you for raising that point — I completely agree with the importance of respecting React’s lifecycle and avoiding interference.

That said, I believe useIsMounted aligns with that principle rather than violating it. It doesn’t attempt to override or short-circuit any part of React’s lifecycle; instead, it acts as a guard mechanism for asynchronous side effects, helping prevent updates to unmounted components — a common source of memory leaks and hard-to-trace bugs.

In fact, this pattern complements React’s lifecycle by acknowledging the asynchronous nature of effects, especially in environments where race conditions or delayed executions (e.g., setTimeout, fetch, or requestAnimationFrame) are involved.

While it’s true that React encourages effects to be scoped correctly, in practice developers still face scenarios where external timing or delayed callbacks can lead to unintended updates. useIsMounted simply provides a safe, minimal way to check component presence without mutating state or interfering with React’s render cycle.

So rather than introducing lifecycle interference, this hook serves as a passive safety utility — one that aligns with React’s declarative philosophy by helping avoid imperative leaks.