🪝 Introduction to useTransition
The useTransition Hook is a React Hook that lets you mark certain state updates as non-urgent transitions. This allows React to prioritize important updates, such as user input, while performing less urgent updates in the background, resulting in a smoother and more responsive user experience.
Important
🎯 Why Use useTransition?
Some state updates, such as filtering a large list or rendering complex content, may take noticeable time to complete. If these updates run with the same priority as user interactions, the interface may appear slow or unresponsive. useTransition tells React that certain updates can be deferred while keeping urgent interactions responsive.
- Keep user interactions responsive.
- Delay expensive UI updates.
- Improve perceived application performance.
- Provide loading feedback during transitions.
⚙️ Syntax
Basic Syntax
const [isPending, startTransition] = useTransition();| Part | Description |
|---|---|
| isPending | Indicates whether a transition is currently in progress. |
| startTransition | Marks state updates as non-urgent transitions. |
🔄 How useTransition Works
💻 Example 1: Basic Usage
Using useTransition
import { useState, useTransition } from "react";
function Search() {
const [query, setQuery] = useState("");
const [results, setResults] = useState([]);
const [isPending, startTransition] = useTransition();
function handleChange(event) {
const value = event.target.value;
setQuery(value);
startTransition(() => {
setResults(searchItems(value));
});
}
return (
<>
<input
value={query}
onChange={handleChange}
/>
{isPending && <p>Loading...</p>}
<ul>
{results.map(item => (
<li key={item.id}>
{item.name}
</li>
))}
</ul>
</>
);
}Typing in the input remains responsive because updating the text field is treated as an urgent update, while calculating the search results is performed as a transition.
💻 Example 2: Switching Tabs
Tab Navigation
import { useState, useTransition } from "react";
function Tabs() {
const [tab, setTab] = useState("home");
const [isPending, startTransition] = useTransition();
function changeTab(nextTab) {
startTransition(() => {
setTab(nextTab);
});
}
return (
<>
<button onClick={() => changeTab("home")}>
Home
</button>
<button onClick={() => changeTab("profile")}>
Profile
</button>
{isPending && <p>Loading...</p>}
</>
);
}If rendering a new tab requires significant work, the transition allows the interface to remain responsive while the new content is prepared.
📊 Urgent Updates vs Transition Updates
| Urgent Updates | Transition Updates |
|---|---|
| Typing into an input. | Rendering filtered results. |
| Button clicks. | Loading large datasets. |
| Checkbox selection. | Switching complex views. |
| Immediate UI feedback. | Expensive rendering work. |
📅 Transition Lifecycle
The user performs an action.
Urgent updates are applied immediately.
startTransition() schedules non-urgent updates.
isPending becomes true while the transition is running.
React completes the transition and updates the interface.
🎯 Common Use Cases
Keep search inputs responsive while updating search results in the background.
Filter large collections without interrupting user interactions.
Switch between complex pages or tabs while maintaining a responsive interface.
Render large lists or expensive components as non-urgent transitions.
⚠️ Common Mistakes
- Wrapping every state update inside startTransition().
- Using transitions for urgent user interactions.
- Ignoring the isPending value when loading feedback is needed.
- Expecting useTransition to make expensive computations faster instead of improving responsiveness.
Warning
📊 useTransition vs useDeferredValue
| Feature | useTransition | useDeferredValue |
|---|---|---|
| Purpose | Delay state updates. | Delay the use of a changing value. |
| Controls | State updates. | Derived values. |
| Returns | isPending and startTransition. | A deferred version of a value. |
| Typical Usage | Navigation, filtering, expensive rendering. | Large lists, search results, expensive computations. |
✅ Best Practices
- Use transitions only for non-urgent updates.
- Keep user input responsive by avoiding expensive synchronous rendering.
- Show loading indicators using isPending when appropriate.
- Profile your application before introducing transitions.
- Use useTransition together with other optimization techniques when necessary.
📚 Official Resource
Learn more about useTransition in the official React documentation at React useTransition Documentation.