System Design plays a crucial role in creating robust, efficient, and scalable software solutions. Oftentimes, while React is one of the most popular front-end web application development frameworks based on JavaScript, there doesn’t seem to be much material connecting it to System Design.
So, on the face of it, they appear completely different from each other. But are they? For beginner or even intermediate developers, it might appear that these concepts are not important. However, advanced developers need to handle projects that keep becoming more complex by the minute and need to fulfill every requirement. This is why they need to learn about these concepts and do everything just right.
In this blog, we’ll present a unique perspective by taking four key concepts of System Design and demonstrating how they can be applied to React.
Let’s first try to understand some of the primary reasons why System Design is considered an essential skill for software engineers:
System Design serves as a blueprint for software development projects. It outlines the architecture, components, interactions, and overall functionality of the system helping in planning and organization.
A well-designed system can handle growth and adapt to changing requirements. It allows for easy scaling and modification without major disruptions, thereby ensuring scalability and flexibility.
Proper System Design ensures optimal resource utilization, minimizing bottlenecks and improving overall performance. It considers factors like caching, load balancing, and effective resource usage ensuring both efficiency as well as performance.
Maintainability is directly connected with reliability. A good design simplifies maintenance tasks, making it easier to fix issues and add new features. It also reduces the risk of errors during development or deployment.
In summary, System Design sets the foundation for the entire software system, making it more efficient, effective, and maintainable in the long run.
React (also known as React.js or ReactJS) is a free and open-source front-end JavaScript library developed by Facebook Inc. It’s widely used for building user interfaces (UIs). Here are some key points that help understand React basics:
React follows a component-based architecture. Developers create reusable UI components, which makes it easier to manage and maintain complex interfaces. React encourages breaking down UIs into smaller, reusable components. These components can be composed together to create a complete UI-enabling component composition.
React is also declarative. It allows us to describe what we want our UI to look like rather than focusing on how to achieve it. This declarative approach simplifies UI development. React also uses a Virtual DOM (Document Object Model). Instead of directly updating the actual DOM, React first updates a lightweight virtual representation of it. This optimization minimizes DOM updates and improves rendering performance.
Another key point to understand is that React is not a framework. React is often referred to as a library. It’s not even exclusive to the web and can be used with other libraries (e.g., React Native for mobile apps). While React has a learning curve and requires some tooling (such as Babel for JSX compilation), it’s powerful and widely adopted.
System Design involves a number of concepts, but some concepts lie at its very core. Let’s first briefly revise what they are:
Scalability refers to a system’s ability to handle increased load or growth without compromising performance. It can be achieved through horizontal scaling (adding more servers) or vertical scaling (upgrading existing servers). In web applications, scalability ensures that the system can handle more users, requests, and data without slowdowns or crashes.
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Performance relates to how efficiently a system executes tasks. It encompasses response time, throughput, and resource utilization. Techniques for improving performance include optimizing algorithms, caching, using content delivery networks (CDNs), and minimizing database queries.
The close relationship between performance and scalability stems from the ability to scale effectively impacting overall performance. A well-designed system can handle increased loads and maintain or improve its performance, keeping response times fast and resource utilization efficient as demand grows. On the other hand, scalability may be hindered by poor performance due to bottlenecks arising from increased user or data demands.
Reliability ensures that a system consistently performs its intended functions without failures or errors. Achieving reliability involves redundancy (backup servers), fault tolerance (handling failures gracefully), and issue monitoring.
Security involves protecting data, systems, and users from unauthorized access, breaches, and attacks. Practices include encryption, authentication, authorization, input validation, and regular security audits.
Now that we have understood the four core system design concepts, let’s see how we can connect them with React.
It might seem unimportant, but interestingly, choosing an organizational approach that suits our project’s size and complexity can significantly increase our project’s scalability. There are a few concepts which can help organize the project:
An easy way of grouping the files is by grouping either by features or modules. Each feature has its directory containing related components, styles, services, and utilities.
One way to organize is using layered (vertical) organization. In this organization, we can group files by functional layers (presentation, data, services). It helps to clearly define responsibilities for each layer in this case.
Another possibility for organizing files is using a Domain-Driven Design (DDD). To understand DDD, businesses can organize files by adjusting folders and subfolders around specific business domains or subdomains. This is especially useful in the case of business expansion.
A third possibility for project organization is to use atomic design. Atomic design involves creating components as building blocks at different levels of abstraction, similar to how the real world is structured. So, think in terms of how atoms are the smallest building blocks. They combine to form molecules, which interact in complex ways in organisms. In the same way, we can use templates and pages and structure our project in an intuitive manner.
Achieving horizontal scaling in a React application involves deploying it on various servers or containers, typically through cloud platforms like AWS, Azure, or Kubernetes. Horizontal scaling allows for the distribution of user requests across multiple instances, resulting in better load balancing and reduced downtime.
When it comes to server-side rendering (SSR) or handling API requests, vertical scaling in a React application can improve server performance.
By vertically scaling a React application, it becomes capable of handling a higher volume of requests and delivering content more rapidly, which is particularly advantageous for applications with demanding computations or extensive datasets. When a React application requires a backend server for data retrieval or complex computations, enhancing the server’s resources can result in faster response times and a more seamless user experience. Although vertical scaling can boost performance, it has capacity restrictions and can create a single point of failure. To ensure resilience and scalability, a balanced approach, which may include horizontal scaling, is necessary.
Any reasonably complex or moderately useful web application must handle the state at any time. We simply cannot avoid the state. However, there are certain best practices that can help keep this intuitive and improve scalability.
The most important aspect to consider here is keeping some state local to components to avoid over-engineering by asking a few questions, such as:
Do other parts of the application care about this data?
Data can be generated in a number of different locations in the app. Not every piece of data needs to be recalled at the global level. Making everything global can significantly affect scalability. To optimize our apps, we can make a list of all such data that needs to be transmitted between different parts of the application and ask whether or not that particular piece of data is really something that must be available globally or can be limited to just a few modules.
Is the same data used by multiple components?
One common use case for reusability occurs when we realize that we are doing the same thing over and over. In other words, in development, we often need to create data, use it, and then immediately discard it.
Do you need to restore this state for debugging?
As developers, we have realized over time that as much as we might not have wanted, a good part of our programming career is actually spent on debugging rather than coding. This is like the gym schedule in some ways. We often want to have chest and arms days every day of the week. But turns out, if we want to have a balanced physique, it would probably be a good idea only to have them once a week each. So, when most of our "coding time" actually ends up fixing bugs and "debugging," it makes sense to ensure we optimize data stored for debugging as well.
Consider using Redux or context for global state
There are two ways we can maintain a global state. One is via the context API and the other via Redux.
The Context API is a built-in React tool that allows us to share values (such as state) between components without explicitly passing props through every level of the component tree. For example, we can use it to manage UI themes, locale preferences, or other simple data.
Redux is a predictable state container for JavaScript apps. It provides a centralized store, actions, and reducers to manage the state. A possible use case for Redux is when dealing with larger, more complex states or when advanced features like middleware, time-travel debugging, and a consistent developer experience are needed.
Test early and often
Another important thing to do for scalability is to start writing automated tests from the beginning. Testing helps catch errors, ensures modularity, and safeguards against production issues. As the project grows, manual testing becomes impractical.
Performance optimization
Rendering performance can be optimized using React.memo for memoization.
React.memo is a higher-order component (HOC) that memoizes functional components. It prevents unnecessary re-renders by comparing the current props with the previous props and re-rendering only when changes are detected. By wrapping a component with React.memo, we can ensure that it only re-renders if its props have changed.
Use cases for React.memo include pure components, expensive computations, and the prevention of unnecessary renders. When applying memoization, we should focus on components that benefit the most, profile our app to measure the impact, and combine memoization with other performance optimizations.
When props or state change, PureComponent performs a shallow comparison on both props and state. It checks if the new values are the same as the old ones. This means that if our props or state are complex objects (nested or deeply structured), PureComponent might miss updates. It only compares at the top level. For simple flat objects or primitive types, PureComponent works well. However, for more complex scenarios, we might consider customizing shouldComponentUpdate() in a regular Component.
There are two ways in which we can evaluate and improve performance in React. One is related to loading performance, and the other to runtime.
For the loading performance, the focus is on compressing and loading code/assets, which includes non-React elements (e.g., images, stylesheets, fonts). The techniques for improving loading performance include minifying and compressing assets to reduce file sizes to speed up loading times, using CDNs (Content Delivery Networks) to serve assets from geographically distributed servers, lazy loading to load assets only when needed (e.g., lazy-loaded images), and code splitting to divide large bundles into smaller chunks to load only what’s necessary.
Whereas for runtime performance, the focus is on CPU usage, rendering efficiency, and React-specific optimizations. Strategies for better runtime performance include memoization tp prevent unnecessary re-renders by memoizing components or using React.memo(), useCallback and useMemo hooks to optimize function and value references, windowing or list virtualization to render only visible items in long lists, or other techniques like immutable data structures to avoid unnecessary object mutations, web workers to offload heavy computations to separate threads or using reselect in Redux to optimize rendering by selecting only necessary data.
Reliability in React applications involves ensuring consistent performance, robustness, and error handling. Here are some practices to enhance reliability:
Error boundaries can be implemented to catch and handle JavaScript errors within components. Error boundaries prevent the entire app from crashing due to a single component error.
Writing comprehensive unit tests using tools like Jest and React Testing Library helps catch issues early and ensures code reliability, besides considering integration and end-to-end tests as well.
We have already discussed state management as it helps choose a reliable solution (e.g., Redux, Mobx, or Context API). Properly managing the application state can prevent unexpected behavior, thereby improving reliability. Using immutable data structures (e.g., Immutable.js or Immer) can avoid accidental state mutations as this ensures predictable behavior and simplifies debugging. Setting up monitoring tools (e.g., Sentry, New Relic, or custom logging) to track errors, performance bottlenecks, and user interactions also helps. Logging can involve monitoring API calls, network requests, and client-side errors.
Git can be used for version control. We just have to follow best practices for branching, merging, and code reviews. Finally, implementing continuous integration/continuous deployment (CI/CD) pipelines helps ensure reliable deployments.
The last aspect that we are going to discuss from the system design perspective is security.
React is designed to be secure by default, but we can enhance this by using data binding with curly braces ({}) to automatically escape values and prevent cross-site scripting (XSS) attacks. We also have to be cautious when rendering HTML attributes; the protection applies to textContent but not attributes.
It is important to validate URLs to ensure they are either http: or https: to prevent javascript-based script injection. Another important aspect is to use native URL parsing functions and match the parsed protocol to an allowed list.
Avoid directly inserting HTML into DOM nodes using dangerouslySetInnerHTML. We can also sanitize content using a library like dompurify before using dangerouslySetInnerHTML.
It makes sense to always avoid direct DOM manipulation. If necessary, use dangerouslySetInnerHTML and sanitize the HTML content.
We must implement server-side rendering securely to prevent potential vulnerabilities.
It is a good practice to regularly update React and its dependencies to benefit from security patches and bug fixes. We should also use tools like npm audit or yarn audit to identify and address vulnerabilities.
Let's recap the significance of integrating System Design principles with React development. While many view System Design as primarily backend-focused, there are valuable principles applicable to the frontend, especially in React. We explored four key principles and demonstrated their practical application in React.
Now that you've grasped the fundamentals of System Design in React, it's time to elevate your skills. With the techniques outlined here, you can create scalable, efficient, and maintainable React applications that meet complex requirements.
Explore our resources on React and System Design interview, where you'll learn from industry experts and gain hands-on experience with real-world projects. We offer courses for all levels, so check them out and start building the skills you need to succeed in React development!
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