Cover Image for ReactJS State vs Props

ReactJS State vs Props

The ReactJS state and props are important concepts used to manage and pass data within your components. However, they serve different purposes and have distinct characteristics:

Props (Properties):

  1. Props are Read-Only: Props are used to pass data from a parent component (the component that renders another component) to its child components. They are read-only, which means child components cannot modify their props.
  2. Passed from Parent: Props are passed down the component tree, from parent to child. They provide a way for parent components to communicate with and control their children.
  3. Immutable: Once props are set for a component, they cannot be changed by that component itself. Any updates to the props must be done by the parent component.
  4. Use for Configuration: Props are commonly used to configure child components, providing them with data or behavior specific to their context. For example, passing a name prop to a Person component to display a person’s name.
  5. Examples of Props:
  • Data passed to a component.
  • Callback functions for event handling.
  • Configuration values.


  1. Component-Specific: State is used to manage component-specific data that can change over time and trigger re-renders. Each component can have its own state.
  2. Mutable: Unlike props, components can update and modify their own state using the setState method. When state changes, React re-renders the component to reflect the new state.
  3. Initialization: State is typically initialized in the constructor of class components or using the useState hook in functional components.
  4. Examples of State:
  • User input (e.g., form fields).
  • Data fetched from an API.
  • UI-related toggles or flags.
  • Component-specific counters or timers.

When to Use Props vs. State:

The decision to use props or state depends on the nature of the data and its management:

  • Props should be used when data is passed from parent to child components, especially when that data is not meant to be modified by the child component.
  • State should be used for data that can change within a component and triggers re-renders. It is used to manage component-specific data and should be kept as minimal as possible to maintain component simplicity.

In summary, props are used for passing data from parent to child components and are read-only, while state is used for managing component-specific data that can change and trigger re-renders, and it is mutable within the component. Understanding when and how to use both props and state is fundamental to building efficient and maintainable React applications.


The Tech Thunder

The Tech Thunder

The Tech Thunder