Feature flags enable controlled feature rollouts without code changes.
They provide a mechanism to test in production and manage features safely.
Feature flags support various use cases like AB testing and Canary releases.
They allow targeting specific user groups for feature access.
Feature flagging systems offer insights into the impact of changes.
Feature flags have become an essential tool in modern software development, offering a way to manage the deployment and release of new features efficiently. They allow developers to control who sees certain features, enabling a more nuanced rollout process without requiring constant code changes.
The primary benefit of using feature flags is the ability to roll out features in a controlled manner. This means that once a feature is ready on the back-end, it can be made visible to users simply by toggling the flag. This approach significantly reduces the risk associated with new releases. If any issues arise, rolling back is straightforward, ensuring stability in production environments.
Feature flags also facilitate testing in production. By activating a feature for a specific subset of users, developers can gather valuable feedback and performance data in real-world scenarios. This method is particularly useful for A/B testing, where different versions of a feature are tested to determine which performs better.
Another critical use of feature flags is as a kill switch. If a feature is not performing as expected or causing issues, it can be quickly turned off without redeploying code, minimizing downtime and potential disruptions to the user experience.
Feature flags are invaluable for managing the transition from monolithic architectures to microservices. They allow teams to gradually migrate features and services, ensuring that each component functions correctly before the entire system is transitioned. This phased approach reduces the complexity and risk of large-scale migrations.
From a business perspective, feature flags empower product owners and non-technical stakeholders to control the user experience. They can decide which features to release and to whom, without needing to involve developers in every decision. This autonomy speeds up the development process and improves the agility of the team.
Implementing feature flags in a React application involves several steps. First, developers need to integrate a feature flagging system like Split.io. After setting up an account, creating a feature flag, or 'split', is straightforward. Each flag should have a unique name and clearly defined behavior for different user groups.
In the application code, developers need to import the necessary dependencies and configure the feature flagging SDK. This typically involves importing components for feature evaluation and wrapping application components to apply feature flags. Conditional rendering is used to determine which elements, such as a delete button, should be visible based on the feature flag's state.
Developers can configure feature flags to target specific users or groups, ensuring that only intended users receive new features. For instance, in a to-do list app, only developers might initially have access to a delete task feature. By adjusting the feature flag settings, this capability can be expanded to more users over time.
Feature flags also provide valuable insights into the impact of changes. By integrating with internal analytics systems, teams can track how different features affect user behavior and application performance. This data-driven approach enables better decision-making and optimization of features based on actual user interactions.
The use of feature flags is a powerful strategy that enhances the development, testing, and delivery of software. They provide a flexible, risk-averse method to manage features, allowing teams to innovate and iterate rapidly while maintaining a stable user experience.
As developers, we release features daily – but how do you ensure those features are working properly in production before you release them to all your users? If you ask me, the answer is feature flags! Feature flags are beneficial because they allow you to test your code in production, perform canary releases, and even conduct A/B testing. The power of React makes it easy to implement these flags. We will walk through how to easily create a feature flag in the UI, install dependencies with npm, and implement your feature flag in your react app.
This talk has been presented at React Summit Remote Edition 2021, check out the latest edition of this React Conference.
A feature flag in React is a technique used to enable or disable features in your application without deploying new code. It allows developers to control the visibility of features based on certain conditions.
Feature flags benefit front-end development by allowing developers to test new features in production, roll back features if issues arise, and control feature visibility without requiring new code deployments. This minimizes risks and improves the development process.
Common use cases for feature flags include testing in production, using them as a kill switch to turn off problematic features, migrating from monoliths to microservices, A/B testing, subscription management, canary releases, and experimentation.
To create a feature flag in Split.io, log in to Split.io, create a free developer account, and then click 'Create Split' on the left pane. Name the split and configure it with the desired settings. This split will act as your feature flag.
You need to install the Split.io JavaScript SDK. Import split treatments and withSplitFactory components from the SDK in your React component to perform feature evaluation and wrap your to-do list component.
In your React app, import the Split.io SDK, instantiate and use the SDK by wrapping your component with withSplitFactory, and use split treatments in your render function. Configure the split instance with your user authentication key and set the desired feature flag names.
Yes, non-technical team members such as product owners can control feature flags using a feature flag management application like Split.io. They can set who can see which features without committing new code.
The 'allow delete' variable in the React app example is used to differentiate between the treatment being on or off. If the treatment is on, users can see the delete tasks button; if off, the delete option is not available.
You can verify which users are targeted by a feature flag in Split.io by checking the browser console logs after running npm start. The logs will show which user is getting the treatment and whether the treatment is set to on or off for that user.
If a feature controlled by a feature flag has bugs, you can temporarily roll back the release by turning off the feature flag. This allows you to disable the problematic feature without deploying new code.
This Talk discusses setting up feature flags with React, which allows for controlled rollouts of new features. Feature flags provide more control without touching the source code and can target specific users or types of users. In React, feature flags can be created and configured using Split.io. Different treatments can be applied to determine if a feature should be shown. Feature flagging provides control and flexibility in development.
We're going to talk about setting up feature flags with React today. Let's say I am a front-end developer working on this to-do list app. And right now, users only have the ability to add tasks to the list. And I want to add the ability to delete tasks. And adding this feature requires back-end work as well because we need a new API endpoint. And I don't know if the back-end change is going to be ready in time. But here's what I've done so far. I have this conditional statement set. And by default, the user is not allowed to delete. So this is the current state. And when I'm testing this feature locally, I flip this boolean to true to test stuff out. And once the back-end is ready and I want my users to be able to see the delete button, then I'm just going to push this commit with the boolean equal to true. And right now, this is working.
2. Using Feature Flags for Controlled Rollouts
Once the back-end is ready, I can push a commit to enable the delete button. Feature flags have various use cases, including testing in prod, kill switches, microservices migration, AB testing, subscription management, Canary releases, and experimentation. Feature flags improve development, testing, and delivery of new features while minimizing risks. They also allow for measuring the impact of changes and providing control over the user experience without code commits.
3. Implementing Controlled Feature Flags
I want to roll out this delete functionality in a controlled way using feature flags. With a feature flagging system, I get more control without touching the source code. I can target specific users or types of users. The treatment controls who can delete tasks. When the treatment is on, the user can delete tasks, and when it's off, they can't.
4. Creating and Configuring Feature Flags in React
In React, instead of hard-coding the ability to delete, we can create a feature flag. To create a feature flag, log in to Split.io and create a split. Install the necessary dependencies and import the JavaScript SDK. Use the split treatments component to evaluate the feature and the width split factory component to wrap the to-do list component. Differentiate between treatment on and off to determine if the delete option should be shown. Configure the split instance with the user's authentication key. When targeted in the feature flag, the delete buttons will be visible. Set debug to true to view the logs in the console. If the user is not targeted, the delete buttons will not appear. Feature flagging provides control and flexibility in development. For more information, visit split.io.
This transcription provides a brief guide to React rendering behavior. It explains the process of rendering, comparing new and old elements, and the importance of pure rendering without side effects. It also covers topics such as batching and double rendering, optimizing rendering and using context and Redux in React. Overall, it offers valuable insights for developers looking to understand and optimize React rendering.
Remix is a web framework built on React Router that focuses on web fundamentals, accessibility, performance, and flexibility. It delivers real HTML and SEO benefits, and allows for automatic updating of meta tags and styles. It provides features like login functionality, session management, and error handling. Remix is a server-rendered framework that can enhance sites with JavaScript but doesn't require it for basic functionality. It aims to create quality HTML-driven documents and is flexible for use with different web technologies and stacks.
The Talk discusses React Forget, a compiler built at Meta that aims to optimize client-side React development. It explores the use of memoization to improve performance and the vision of Forget to automatically determine dependencies at build time. Forget is named with an F-word pun and has the potential to optimize server builds and enable dead code elimination. The team plans to make Forget open-source and is focused on ensuring its quality before release.
Today's Talk explores the use of the useEffect hook in React development, covering topics such as fetching data, handling race conditions and cleanup, and optimizing performance. It also discusses the correct use of useEffect in React 18, the distinction between Activity Effects and Action Effects, and the potential misuse of useEffect. The Talk highlights the benefits of using useQuery or SWR for data fetching, the problems with using useEffect for initializing global singletons, and the use of state machines for handling effects. The speaker also recommends exploring the beta React docs and using tools like the stately.ai editor for visualizing state machines.
Routing in React 18 brings a native app-like user experience and allows applications to transition between different environments. React Router and Next.js have different approaches to routing, with React Router using component-based routing and Next.js using file system-based routing. React server components provide the primitives to address the disadvantages of multipage applications while maintaining the same user experience. Improving navigation and routing in React involves including loading UI, pre-rendering parts of the screen, and using server components for more performant experiences. Next.js and Remix are moving towards a converging solution by combining component-based routing with file system routing.
Cecilia Martinez, a technical account manager at Cypress, discusses network requests in Cypress and demonstrates commands like cydot request and SCI.INTERCEPT. She also explains dynamic matching and aliasing, network stubbing, and the pros and cons of using real server responses versus stubbing. The talk covers logging request responses, testing front-end and backend API, handling list length and DOM traversal, lazy loading, and provides resources for beginners to learn Cypress.
Ivan’s first attempts at performance debugging were chaotic. He would see a slow interaction, try a random optimization, see that it didn't help, and keep trying other optimizations until he found the right one (or gave up). Back then, Ivan didn’t know how to use performance devtools well. He would do a recording in Chrome DevTools or React Profiler, poke around it, try clicking random things, and then close it in frustration a few minutes later. Now, Ivan knows exactly where and what to look for. And in this workshop, Ivan will teach you that too. Here’s how this is going to work. We’ll take a slow app → debug it (using tools like Chrome DevTools, React Profiler, and why-did-you-render) → pinpoint the bottleneck → and then repeat, several times more. We won’t talk about the solutions (in 90% of the cases, it’s just the ol’ regular useMemo() or memo()). But we’ll talk about everything that comes before – and learn how to analyze any React performance problem, step by step. (Note: This workshop is best suited for engineers who are already familiar with how useMemo() and memo() work – but want to get better at using the performance tools around React. Also, we’ll be covering interaction performance, not load speed, so you won’t hear a word about Lighthouse 🤐)
With the release of React 18 we finally get the long awaited concurrent rendering. But how is that going to affect your application? What are the benefits of concurrent rendering in React? What do you need to do to switch to concurrent rendering when you upgrade to React 18? And what if you don’t want or can’t use concurrent rendering yet?
There are some behavior changes you need to be aware of! In this workshop we will cover all of those subjects and more.
Join me with your laptop in this interactive workshop. You will see how easy it is to switch to concurrent rendering in your React application. You will learn all about concurrent rendering, SuspenseList, the startTransition API and more.
The addition of the hooks API to React was quite a major change. Before hooks most components had to be class based. Now, with hooks, these are often much simpler functional components. Hooks can be really simple to use. Almost deceptively simple. Because there are still plenty of ways you can mess up with hooks. And it often turns out there are many ways where you can improve your components a better understanding of how each React hook can be used.You will learn all about the pros and cons of the various hooks. You will learn when to use useState() versus useReducer(). We will look at using useContext() efficiently. You will see when to use useLayoutEffect() and when useEffect() is better.
ReactJS is wildly popular and thus wildly supported. TypeScript is increasingly popular, and thus increasingly supported.
The two together? Not as much. Given that they both change quickly, it's hard to find accurate learning materials.
React+TypeScript, with JetBrains IDEs? That three-part combination is the topic of this series. We'll show a little about a lot. Meaning, the key steps to getting productive, in the IDE, for React projects using TypeScript. Along the way we'll show test-driven development and emphasize tips-and-tricks in the IDE.
In this workshop, you'll learn how to build your first full stack dapp on the Ethereum blockchain, reading and writing data to the network, and connecting a front end application to the contract you've deployed. By the end of the workshop, you'll understand how to set up a full stack development environment, run a local node, and interact with any smart contract using React, HardHat, and Ethers.js.
React Testing Library is a great framework for React component tests because there are a lot of questions it answers for you, so you don’t need to worry about those questions. But that doesn’t mean testing is easy. There are still a lot of questions you have to figure out for yourself: How many component tests should you write vs end-to-end tests or lower-level unit tests? How can you test a certain line of code that is tricky to test? And what in the world are you supposed to do about that persistent act() warning? In this three-hour workshop we’ll introduce React Testing Library along with a mental model for how to think about designing your component tests. This mental model will help you see how to test each bit of logic, whether or not to mock dependencies, and will help improve the design of your components. You’ll walk away with the tools, techniques, and principles you need to implement low-cost, high-value component tests. Table of contents- The different kinds of React application tests, and where component tests fit in- A mental model for thinking about the inputs and outputs of the components you test- Options for selecting DOM elements to verify and interact with them- The value of mocks and why they shouldn’t be avoided- The challenges with asynchrony in RTL tests and how to handle them Prerequisites- Familiarity with building applications with React- Basic experience writing automated tests with Jest or another unit testing framework- You do not need any experience with React Testing Library- Machine setup: Node LTS, Yarn
Comments