ReactJS Q & A


How to update ‘state’ in React?

In React, state represents the mutable data within a component that can influence its behavior and render output. React has a defined mechanism for updating state to ensure optimal performance and maintainability of the application.

For class-based components, React provides the `this.setState()` method. Instead of mutating the state directly, which is a no-go in React’s paradigm, `this.setState()` is used to signal the framework about desired state changes. This method is asynchronous, serving a dual purpose: it batches multiple updates for performance and ensures that the view stays in sync with the data. When using `this.setState()`, it’s essential to be aware that since it’s asynchronous, relying on the current state to compute the next state can lead to inconsistencies. Instead, React advises using a function with `this.setState()` that receives the previous state and props as its arguments, ensuring accurate updates.

In functional components, React introduced the `useState` hook to handle state. The `useState` hook provides a more direct way to establish and update component state. When updating state using this hook, especially when the next state relies on the previous one, it’s recommended to use a function to ensure that updates are accurate, owing to the asynchronous nature of state updates.

Regardless of the mechanism employed, it’s crucial to treat state as immutable. Rather than modifying state objects or arrays directly, always produce and return a new version. This approach not only adheres to best practices around immutability but also ensures that React can efficiently identify changes and update the UI accordingly.

Previously at
Flag Argentina
time icon
Seasoned Software Engineer specializing in React.js development. Over 5 years of experience crafting dynamic web solutions and collaborating with cross-functional teams.