ReactJS Q & A


What is the difference between state and props in React?

In the realm of React, both state and props play critical roles in determining how a component renders and behaves, but they serve distinct purposes and have unique characteristics.

Props (or properties) are the parameters passed from a parent component to a child component. Think of them as external influences that dictate specific aspects or functionalities of a child component. They are read-only from the perspective of the receiving component, ensuring a unidirectional data flow. This immutability of props ensures predictability, making components easier to understand and debug. Components receive props as a single set of values, and they can use these values to render content or determine behavior. However, within the component’s boundary, these values cannot be changed directly.

On the other hand, state is internal to a component. It represents any data that can change over time and affect the component’s behavior or rendering output. Unlike props, state is mutable. Components can initialize, read, and modify their own state. When state changes, it triggers a re-render of the component, allowing for dynamic and interactive user interfaces. State is used for data that is expected to change and cause the interface to update, reflecting those changes.

A simple way to differentiate is by understanding their sources of value: while props get their value from a parent component and remain unchanged throughout a component’s life, state’s value is managed within the component itself and can change over time.

While both state and props are fundamental to React’s component model, they serve different purposes. Props allow components to be reusable and configurable by passing in data and behavior, whereas state enables components to be dynamic and responsive to user interactions or other internal changes.