reactjs / reactjs/react.dev

[Bug]: Documentation for hooks: warning about infinite loop useEffect with state update is not prominent

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bug: unconfirmed
主要語言
JavaScript
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描述

Summary

Description

The documentation for React Hooks (especially useEffect) mentions that updating state inside an effect without a proper dependency array can cause infinite loops, but this warning is not highlighted prominently. Many beginners miss this and end up in render loops.

Given how frequently this issue occurs, the documentation should emphasize it more clearly, perhaps with a bold warning and a simple example.

Example that causes confusion

import React, { useState, useEffect } from "react";

function MyComponent() {
  const [count, setCount] = useState(0);

  useEffect(() => {
    setCount(c => c + 1);
  }); // Missing dependency array

  return <div>{count}</div>;
}

Running this causes an infinite render loop because setCount triggers a state update on every render, re-invoking useEffect.

Actual behavior

  • Docs mention dependency arrays briefly, but the infinite loop risk is not highlighted enough.
  • Beginners often miss this and think React is “re-rendering infinitely” due to a bug.

Expected behavior

  • The official docs should include a bold, visible warning in the useEffect section, such as:

Warning: Omitting the dependency array causes the effect to run after every render, potentially leading to infinite loops if state or props are updated inside.

  • Include a small “bad vs. good” code example pair to clarify.

Why this matters

This is one of the most common pitfalls for new React developers. Making the warning prominent in official docs will help reduce confusion and GitHub issues related to infinite re-renders.

Environment

  • React version: 18.x (or whichever version is current)
  • Browser: Chrome 118
  • OS: Windows 11 / Ubuntu 22.04

Additional info

Several discussions online highlight this confusion; here’s one example:
https://www.reddit.com/r/reactjs/comments/oomo1w/what_are_the_biggest_issues_you_see_with_react_in/

Page

https://react.dev/reference/react/useEffect

Details

The warning could be moved closer to the main example or highlighted with a strong visual cue (e.g., bold text or a red caution box).
This would help prevent confusion among new React users who encounter infinite loop behavior.

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  4. 送出 Pull Request,並在描述裡引用這個 Issue 編號。

研究方向

從 issue 中連結的 useEffect 參考頁面開始,檢查目前對依賴陣列和主要範例的說明方式。突顯關於無限迴圈的警告,並加入一個簡潔的錯誤範例與正確範例,然後確認頁面清楚說明了在沒有依賴陣列的情況下從 effect 更新 state 的風險。

由索引模型根據 Issue 內容生成。

評估

技術堆疊
javascript, react
領域
documentation
Issue 類型
文件
難度
2/5
預估耗時
1-3 小時
活躍度
停滯
描述清晰度
描述清楚
新手友好度
52/100

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