😵‍💫 5 useEffect Dependency Myths That Cause Infinite Re-renders

“If your React app is re-rendering forever, chances are… your dependency array is lying to you.” 😅

We’ve all been there:
 You add a simple useEffect, refresh the page… and boom — infinite re-renders, API calls going brrr, laptop fan sounding like a jet engine. ✈️

Let’s break down 5 common myths about useEffect dependencies that silently cause performance issues and bugs — and how to fix them properly.

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❌ Myth 1: “Empty dependency array means it runs once forever”

useEffect(() => {
  fetchData();
}, []);

🚨 Problem

This only runs once per component mount, not forever.
 If props/state used inside fetchData change later, your effect becomes stale.

✅ Better

useEffect(() => {
  fetchData(userId);
}, [userId]);

📌 Rule:
 If you use a variable inside useEffect, it belongs in dependencies.

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❌ Myth 2: “Functions don’t need to be added as dependencies”

useEffect(() => {
  loadData();
}, []);

🚨 Problem

Functions are re-created on every render.
 React sees a new reference → effect can behave unpredictably.

✅ Fix with useCallback

const loadData = useCallback(() => {
  console.log("Fetching...");
}, []);

useEffect(() => {
  loadData();
}, [loadData]);

📌 Rule:
 Functions are dependencies too.

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❌ Myth 3: “Objects and arrays are safe in dependency arrays”

useEffect(() => {
  console.log(filters);
}, [filters]);

🚨 Problem

Even if filters content is same, its reference changes → infinite re-renders.

✅ Fix with memoization

const filters = useMemo(() => ({ status: "active" }), []);

useEffect(() => {
  console.log(filters);
}, [filters]);

📌 Rule:
 Objects & arrays change reference easily → memoize them.

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❌ Myth 4: “If it causes loops, just remove it from dependencies”

useEffect(() => {
  setCount(count + 1);
}, []);

🚨 Problem

This creates stale state bugs.

✅ Correct approach

useEffect(() => {
  setCount((prev) => prev + 1);
}, []);

📌 Rule:
 Never hide dependency bugs by deleting dependencies.

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❌ Myth 5: “ESLint rules are optional warnings”

React’s ESLint rule:

react-hooks/exhaustive-deps

🚨 Problem

Ignoring this rule leads to:

• Stale closures
• Hidden bugs
• Unexpected behavior in production

✅ Best practice

Fix the code, don’t silence the warning.

useEffect(() => {
  fetchUser(userId);
}, [userId]);

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🧠 Quick Mental Model

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⚡ Real-World Infinite Loop Example

❌ Bad:

useEffect(() => {
  setUser({ name: "Dev" });
}, [user]);

✅ Good:

useEffect(() => {
  setUser((prev) => ({ ...prev, name: "Dev" }));
}, []);

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🧩 TL;DR

• useEffect re-runs when dependencies change
• Functions & objects change references
• ESLint warnings exist for a reason
• Infinite loops = logic problem, not React problem

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📌 Final Thought

Most infinite re-renders are not React bugs — 
 they’re dependency misunderstandings.

Once you master useEffect dependencies, your apps become:

• Faster ⚡
• Cleaner 🧹
• Easier to debug 🧠

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Writer : Akiko Kawai

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— Bhuwan Chettri
Editor, CodeToDeploy

CodeToDeploy Is a Tech-Focused Publication Helping Students, Professionals, And Creators Stay Ahead with AI, Coding, Cloud, Digital Tools, And Career Growth Insights.