reactjs / reactjs/react.dev

Clarify why useEffect() may need exhaustive deps

Open
#3,763 4 comments 2 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Dominant language
JavaScript
Stars
11.8k
Forks
7.9k
Avg merge
1d 11h
Merged PRs (30d)
11

Description

I may be having a... moment, but in Conditionally firing an effect, is this sentence accurate?

If you use this optimization, make sure the array includes all values from the component scope (such as props and state) that change over time and that are used by the effect. Otherwise, your code will reference stale values from previous renders.

Doesn't useEffect capture the latest props and state the moment any of its dependencies change? What can happen is the effect misses some updates when things it references change and they're not included as deps, but when it does run the props and state are "fresh" (pertaining to the latest render), are they not?

(Edit: removed unrelated point)

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the linked “Conditionally firing an effect” section and review the sentence about values from the component scope against the documented useEffect dependency behavior. Done means the wording accurately explains what happens when referenced values are omitted from the dependency array.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, react
Domain
documentation
Issue type
Documentation
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.