React/SEO Best Practices Flashcards
What is server-side rendering (SSR) in React and how does it improve SEO?
SSR is the process of rendering components on the server rather than on the client. This improves SEO by ensuring that search engines can crawl and index the content of a React application, as the rendered page is returned to the browser with all its content already populated.
How can you implement SSR in a React application?
SSR can be implemented in a React application using a framework like Next.js, which provides out-of-the-box SSR capabilities, or by using libraries such as ‘react-dom/server’ with Node.js to manually render components to HTML on the server.
Why is code-splitting important for React applications and Lighthouse scores?
Code-splitting is important because it allows you to divide your code into smaller chunks which can then be loaded on demand. This reduces the initial load time of your application, improving performance metrics that Lighthouse measures such as First Contentful Paint (FCP) and Time to Interactive (TTI).
How do you implement code-splitting in a React application?
Code-splitting in React can be implemented using dynamic import() syntax, which allows components to be loaded only when they are needed. React Router and libraries like Loadable Components can also be used for route-based code-splitting.
What is the role of the service worker in a React application concerning performance?
A service worker acts as a proxy between the web application and the network. It can cache assets and API responses, allowing for faster load times and offline functionality, which positively affects the performance score in Lighthouse.
How can you minimize main-thread work in a React application?
To minimize main-thread work, optimize your JavaScript by reducing long-running tasks, splitting up tasks using window.requestIdleCallback(), removing unused code, minimizing library use, and optimizing component rendering using React.memo and PureComponent.
Explain the importance of image optimization in React for performance and SEO.
Optimizing images reduces their file size without significantly affecting quality, leading to faster page loads, which is crucial for both user experience and SEO. Use modern image formats like WebP, and implement lazy loading for images below the fold.
How can you optimize CSS delivery in React to improve performance?
Optimize CSS delivery by eliminating unused CSS, using minification, inlining critical CSS, and deferring non-critical CSS. Tools like PurifyCSS can help remove unused styles and styled-components can inline critical CSS automatically.
Describe how to use React’s Profiler API to improve performance.
React’s Profiler API measures how often a component renders and the “cost” of rendering. By identifying components that render too often with high costs, you can target performance optimizations more effectively, such as memoizing with React.memo or optimizing state updates.
What is the importance of using semantic HTML elements in React applications for SEO?
Semantic HTML elements like <header>, <footer>, <article>, and <section> provide meaningful information about the content of the page to search engines, improving the content’s accessibility and relevance in search results.
What is lazy loading and how does it benefit a React application?
Lazy loading is a design pattern that delays the loading of non-critical resources at page load time. In React, you can use React.lazy for component-level lazy loading. This improves performance by reducing the initial load time and minimizes the amount of code needed during the initial load.
How do React Hooks affect performance?
Proper use of React Hooks like useState, useEffect, and useMemo can help in optimizing component updates, side effects, and computations, leading to better performance. Misuse, however, can lead to unnecessary re-renders.
How can you optimize forms in React for performance?
For forms in React, use controlled components with local state and update the state in the onChange event. This minimizes the number of re-renders. For complex forms, consider using libraries like Formik or React Hook Form, which optimize re-rendering.
Explain how HTTP/2 can improve the performance of a React web app.
HTTP/2 provides performance improvements over HTTP/1.1 with features like server push, stream multiplexing, and header compression, leading to faster page load times due to more efficient use of network resources.
How does the React Virtual DOM improve app performance?
The Virtual DOM is a lightweight copy of the actual DOM. React uses it to batch updates and minimize direct manipulations of the DOM, which is a performance-intensive operation, thus making updates faster and more efficient.
