Aug 15, 2026· 5 min read
React useState Explained with Practical Examples
useState is the React Hook that lets a component remember values between renders. Learn how it works with practical examples.
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Aug 15, 2026· 5 min read
How to Update State Based on Previous State in React
Update React state with an updater function when the next value depends on the previous one. See why it avoids stale reads and double-click bugs.
React
Aug 15, 2026· 5 min read
Why React State Does Not Update Immediately
React state only changes for the next render, not the line that sets it. Learn why the value looks stale and how snapshots and batching work.
React
Aug 15, 2026· 5 min read
How to Update Objects in React State
Update objects in React state by replacing them with new copies instead of mutating. Use the spread syntax for flat fields and nested updates.
React
Aug 15, 2026· 5 min read
How to Update Arrays in React State
Update arrays in React state by replacing them with new arrays. Use spread, filter, map, and slice instead of push and splice.
React
Aug 15, 2026· 5 min read
How to Remove, Replace, and Reorder Array Items in State
Remove, replace, and reorder array items in React state with filter, map, and a copied array. Keep every list update immutable.
React
Aug 15, 2026· 5 min read
How to Initialize State Lazily with useState
Initialize useState lazily by passing an initializer function. React runs it once, so expensive setup is not repeated on every render.
React
Aug 15, 2026· 5 min read
How React Batches State Updates
React batches state updates by waiting for an event handler to finish, then applying every change in one re-render. See how batching works.
React
Aug 15, 2026· 5 min read
When to Use One State Object vs Multiple useState Hooks
Use one state object for values that change together and multiple useState hooks for values that change independently. See the deciding rule.
React
Aug 15, 2026· 5 min read
How to Reset State in React
Reset React state by setting it back to the initial value or remounting the component with a new key. Pick the right approach for each case.
React
Aug 15, 2026· 5 min read
How to Preserve and Reset State with Component Keys
Preserve or reset React state with a component key. A changing key remounts the component and starts its state over.
React
Aug 15, 2026· 5 min read
Testing Reducers in React Without Rendering Components
Test React reducers as pure functions with Vitest: call the reducer with a state and an action, assert the result, and check for mutation.
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