🚀 Understanding useDeferredValue in React (with Examples)

Ever noticed your React app lagging when typing into an input box? Maybe you’re doing some heavy work like filtering a large list or rendering charts while the user types.

Let me show you a built-in React hook that can help: useDeferredValue

😩 The Problem

Imagine this code:

<input value={text} onChange={(e) => setText(e.target.value)} />
<HeavyComponent query={text} />

Each keystroke causes HeavyComponent to re-render immediately — even if the user is typing fast. This leads to poor performance and sluggish UI.

🧠 The Concept

useDeferredValue(value) tells React:

“Hey, this value changes a lot, but you don’t have to act on it immediately.”

It lets the UI stay responsive, and updates the heavy parts a little later (as a lower-priority render).

🌀 Step-by-step how useDeferredValue works:

1. 🧍 User types "hello" into the search box.
2. 🎯 The input value (searchTerm) updates immediately to "hello".
3. 🕐 But the filtered data component receives deferredSearchTerm, which may still be "hell" for a moment.
4. 🧘 React prioritizes the text input rendering first.
5. 🛫 Once it's done with urgent work, React updates deferredSearchTerm to "hello", triggering the expensive render.

✅ This results in smoother typing, especially when rendering heavy UI (tables, charts, etc.)

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🛠 How to Use It

import { useState, useDeferredValue } from "react";

function App() {
  const [input, setInput] = useState("");
  const deferredInput = useDeferredValue(input);

  return (
    <>
      <input value={input} onChange={(e) => setInput(e.target.value)} />
      <HeavyComponent query={deferredInput} />
    </>
  );
}

✅ Now HeavyComponent updates slightly delayed\
✅ Your input box stays buttery smooth

⚙️ Improve More with React.memo

React still checks whether HeavyComponent needs to re-render — even if deferredInput hasn’t changed.

So wrap it with React.memo() to avoid unnecessary work:

const HeavyComponent = React.memo(({ query }) => {
  // Imagine heavy filtering/rendering here
  return <div>Results for: {query}</div>;
});

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🧪 Before vs After

Feature	❌ Before useDeferredValue	✅ After useDeferredValue
Typing responsiveness	😵 Sluggish / laggy	🚀 Smooth and responsive
Re-render behavior	Every keystroke triggers render	Render is deferred
Input experience	Feels delayed	Feels instant
Coding complexity	Simple	Still simple
Performance with heavy components	Poor	Much better

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🧠 When Should You Use It?

• 💬 Live search inputs
• 📊 Heavy filtering
• 🧮 Expensive UI calculations
• 🚫 Not for critical real-time updates (like form validation)💬 Live search

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🚀 Benefit of useDeferredValue + memo

• Improve input responsiveness even when rendering heavy UI (e.g. large table, charts).
• Reduce unnecessary renders and speed up perceived performance.
• Let users type/search freely without UI lag.
• Easy to combine with React.memo, useMemo, or charting libraries.

📊 Great for Visualizing Large or Live Data

Using useDeferredValue with React.memo is especially useful when dealing with:

• Real-time charts (like stock prices, KPI dashboards)
• Heavy data visualizations (heatmaps, large graphs)
• UI interactions (search, filter, zoom/pan on visual elements)
• Avoiding expensive chart re-renders on every keystroke

With this combo, your visual components stay responsive and performant, even under pressure 💨

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📦 React Compatibility

useDeferredValue is available from React 18 onwards.

Make sure you're using at least react@18.0.0 and react-dom@18.0.0.

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✅ Summary

• useDeferredValue is your friend for smooth UX
• It tells React to “chill” and update later
• Use it with React.memo to supercharge performance

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🧩 Bonus Example: Defer Updates After Button Click

useDeferredValue isn't just for inputs — it's useful anytime a value changes rapidly and triggers heavy work.

Here’s an example where we defer updates after clicking a button that filters a large list:

📌 Scenario: Selecting a category to filter items

const ItemList = React.memo(({ category }) => {
  const filteredItems = useMemo(() => {
    // Simulate heavy computation
    return filterList(allItems, category);
  }, [category]);

  return (
    <ul>
      {filteredItems.map((item) => (
        <li key={item.id}>{item.name}</li>
      ))}
    </ul>
  );
});

import { useState, useDeferredValue, useMemo } from "react";

function App() {
  const [category, setCategory] = useState("all");
  const deferredCategory = useDeferredValue(category);

  return (
    <div>
      <button onClick={() => setCategory("books")}>Books</button>
      <button onClick={() => setCategory("movies")}>Movies</button>
      <ItemList category={deferredCategory} />
    </div>
  );
}

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🧪 Live Demo

Try out the comparison of using useDeferredValue with React.memo vs without it:

👉 Live Example on StackBlitz

This demo allows you to filter a large table of 20,000 rows using an input field and compare the rendering behavior across two tabs:

• Without useDeferredValue: The table updates instantly with every keystroke, causing noticeable lag.
• With useDeferredValue + React.memo: The input stays responsive while the table updates in a deferred manner, leading to a smoother UX.

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Thanks for reading!
ref: https://react.dev/reference/react/useDeferredValue