In React.js, there are two types of components: PureComponent and Component. In this blog post, we’ll explain the difference between these two types of components and when to use each one.

What is a React Component?

Before we dive into the differences between PureComponent and Component, let’s first define what a React Component is. A React Component is a reusable piece of UI that can be rendered multiple times with different props (properties) and state. It can be created as a class component or a functional component.

In class components, we define a class that extends the React.Component class and implement the render method that returns a React element. In functional components, we define a function that takes props as input and returns a React element.

What is a PureComponent?

A PureComponent is a subclass of the React.Component class. It’s a component that implements the shouldComponentUpdate lifecycle method with a shallow comparison of the component’s props and state. This means that a PureComponent will only re-render if its props or state have changed.

When the shouldComponentUpdate method returns false, the component will not re-render, which can improve the performance of the application. Since PureComponent automatically implements the shouldComponentUpdate method, it can be used in place of a regular Component in some cases.

What is a Component?

A Component is the base class for all React components. It’s a class that implements the render method and can have state and props. Unlike PureComponent, a Component does not implement the shouldComponentUpdate method by default. This means that a Component will always re-render when its props or state have changed.

When to use PureComponent vs. Component

The decision to use a PureComponent or a Component depends on the specific requirements of the component and the performance needs of the application.

Use PureComponent when:

• The component has no side effects
• The component’s props and state are immutable
• The component’s render method is a pure function of its props and state
• The component does not rely on any context or external dependencies

In these cases, PureComponent can help improve performance by preventing unnecessary re-renders.

Use Component when:

• The component has side effects
• The component’s props or state are mutable
• The component’s render method relies on external data or context

In these cases, you should use a Component to ensure that the component is always re-rendered when necessary.

Conclusion

In summary, PureComponent and Component are two types of components in React.js. PureComponent implements the shouldComponentUpdate method with a shallow comparison of props and state, while Component does not. The decision to use one or the other depends on the specific requirements of the component and the performance needs of the application. By understanding the differences between these two types of components, you can make informed decisions when building your React.js applications.