welldone-software/why-did-you-render

Show line where hook that changed is used (feature request)

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#191 opened on Apr 27, 2021

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enhancementgood first issuehelp wanted

Description

I currently have a very big hook, with dozens of useStates, lots of them have empty arrays which trigger unncesary re-renders. But I don't know which is the one doing it each time wdyr logs it's output. I get:

Re-rendered because of hook changes: 
[hook useState result]
...diff

When would be very useful for me is:

Re-rendered because of hook changes:
[hook useState result] (someRandomHook.ts:34)
...diff

Knowing which hook is changing would be useful, specially in nested hooks scenarios, for example I have a hook which uses a hook, and that internal one has state, but wdyr does not even specify which hook is that useState from (I guess react makes no distinction, it only cares about hook declaration order, so not sure how possible would this feature request be.)

Contributor guide

Tech stack
javascriptreact
Domain
performancedeveloper experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Understanding of React hooksFamiliarity with why did you render library source code
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
The issue requests to show the file and line number where a hook change originates. Start by examining the library's core files, particularly how it patches useState and other hooks (e.g., in src/monitorHooks.js or similar). Look for any existing stack trace collection or the ability to add Error().stack to capture the call site. Note that React does not naturally provide this info, but you could use a custom wrapper or monkey patch. Check if there are any comments or related PRs (none linked). A concrete approach: modify the hook patching to wrap the state setter with a function that captures the stack when called, then include that in the log output. Be aware of performance implications.