Conditional Rendering in React

Introduction

Conditional rendering in React.js, refers to the technique of dynamically rendering different content or components based on certain conditions or criteria. It allows developers to control what is displayed to the user based on the current state of the application, user interactions, or data fetched from APIs. Additionally, it’s instrumental in implementing various fundamental React UI principles such as client-side routing and lazy loading. In React, your components may frequently require displaying diverse content based on varying conditions. To achieve this, you can employ syntax such as && operators, and the ternary ? : operator for conditional rendering of JSX.

Conditional Rendering in React using ternary(?) operator

The ternary operator (condition ? true : false) is often used for inline conditional rendering in JSX. Here’s how you can use it:

Conditional Rendering in React using AND(&&) operator

You can use the logical && operator for rendering a single element or component based on a condition. This is useful for rendering elements conditionally without an else clause.

In this case:

• If val<=4, it renders <p>Number is smaller than 5</p>.
• If val>4 , it renders <p>Number is equal or greater than 5</p>.

Advantages of Conditional Rendering

• Notably contributing to faster load times in applications.
• The load time of a web application is directly impacted by the size of its Document Object Model (DOM) during loading. Maintaining a minimal DOM, particularly by excluding elements that are not immediately visible to users until they scroll down, is crucial for optimal performance.
• In this scenario, lazy loading, a widely used technique for deferring resource loading until necessary, can be employed. By implementing lazy loading, components are rendered only when users scroll down to bring them into view. For instance, the react-lazyload library, a popular choice for lazy loading in React, utilizes conditional rendering to display components solely when they become visible to users in the browser viewport.
• Furthermore, conditional rendering plays a significant role in enhancing user experience. It facilitates UI customization based on user properties, such as authentication status (e.g., displaying a login button for unauthenticated users and a logout button for authenticated ones) and access privileges (e.g., presenting editing controls or detailed analytics to content owners while showing limited information to non-owners).
• Moreover, conditional rendering aids in managing client-side operations gracefully, such as data fetching and communication with the backend. For instance, a loading bar can be conditionally rendered during ongoing operations, or an empty list can be hidden while data is fetched from a remote source.
• Additionally, conditional rendering enables the implementation of client-side routing in single-page React applications, exemplified by packages like react-router.

Conclusion

In summary, conditional rendering stands as a potent capability in React, empowering developers to craft dynamic user interfaces. By proficiently leveraging JavaScript operators, expressions, and React conditional rendering techniques, developers can seamlessly render components based on the application’s state or props. Prioritizing readability and maintainability in your conditional rendering logic is essential, fostering scalability and comprehensibility in React applications.

Frequently Asked Questions