Should we have business logic in the UI?

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The talk focuses on building a quiz game application using React, emphasizing the importance of separating business logic from the UI. The speaker discusses the use of React hooks for managing state and functionalities, and the benefits of leveraging the publish-subscribe pattern with the 'meet' library to manage events. They highlight the significance of domain-driven design (DDD) and onion architecture for organizing code around business ideas, making it easier to test and maintain. Key features like adding sounds, creating a lobby, and implementing animations are mentioned, along with strategies for handling user interactions and game state efficiently. The speaker also covers the use of feature flags for testing new functionalities and managing complex states.

From Author:

How many times did you say or hear “this is business logic, it should not be here”?

In this workshop, we will create a modern frontend application using old patterns and you will learn how to build apps that have decoupled UI and services.

We will start with a React application that has its whole logic in the UI. Then step by step we will extract the rules and operations to hit that sweet spot of independence.

This workshop has been presented at JSNation 2022, check out the latest edition of this JavaScript Conference.

FAQ

Samuel's presentation focuses on building a quiz game application using React. He discusses various steps involved in the development process, including starting with existing code, implementing refactors, adding new features, and handling user interactions.

Samuel plans to handle user interactions by starting with a UI application and progressively moving functionalities out of the React hook. He also mentions managing user interactions through the game by implementing features like starting the game on user command instead of automatically.

Samuel intends to implement various features in the quiz game, including adding more sounds, creating a lobby to control the game start, and implementing feature flags. Additionally, he plans to add a 'Dan animation' inspired by Mortal Kombat and modify character names based on user feedback.

Samuel discusses using React for the front-end development, leveraging React hooks for managing state and functionalities, and utilizing a publish-subscribe pattern with the 'meet' library to manage events. He also mentions using branches for version control to keep up with changes in the group.

During the session, Samuel addresses changes by allowing participants to checkout different branches to sync with the latest code. He explains that some steps in the development process might be quicker or longer than expected, averaging about 15 minutes per step.

The educational goal of Samuel's presentation is to demonstrate effective methods in building and refactoring a React application, particularly a quiz game. This includes managing state, handling events, and integrating user feedback into the development process.

Samuel proposes to manage complex features like animations by integrating them into the quiz game using conditional rendering based on the game's state and specific events, such as achieving a combo in the game, which triggers the 'Dan animation'.

Samuel suggests using React hooks to manage game state and user interactions, alongside a publish-subscribe pattern to decouple the game logic from UI events. This approach helps in managing complex states and interactions more efficiently.

Samuel recommends using version control branches to manage and debug the game development process effectively. He encourages participants to checkout different branches if they miss some code or need to sync up, allowing for continuous integration and testing.

Feature flags in Samuel's development process allow for testing new features selectively and controlling which features are active during the game runtime. This method provides flexibility in testing and rolling out new functionalities incrementally.

Samuel Pinto
Samuel Pinto
148 min
04 Jul, 2022

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Video Transcription

1. Introduction to the Quiz Game Development

Short description:

My name is Samuel P. You can call me Sam. We will start by showing what we are building and then start some refactors. We will move things out of the component and use a React hook. After a small break, we will move to an application. We will have a refactor and make the application work triggered by something else. We will add more sounds to the test and create a lobby for the game. We will also create a Dan animation and a feature to change the name of the person's picture. Any questions so far?

So my name is Samuel. Samuel P. You can call me Sam if you wish. It's easier. I think it's a more universal name, Sam. I think I look more like this than this. Yeah, the tissues. So we have some contacts. If you want to reach me after the conference to clarify some questions, if you want to learn more about what I'm talking today. And what they're talking about today is all of this.

So I put 15 minutes in each step. But this will go more up to your speed. So some of them are way quicker than 15. Others are a bit longer than 15. But in average, they will be 15 minutes. So we will start to just show what are we building. Or in this case, rebuilding, because we already have something running. And we will make it in a different way. Let's use a different word for this. And I will share the code that we're starting with. And then we'll start some refactors on it. And we have a small break. We have two breaks. Three breaks, ten minutes each.

So in each step, it's okay if you miss some code. You can always check out branch and you'll be up to the speed of the group. It would be nice if you can do it by yourself. You some reason, you have to go to the door, you have something in the oven and you have to take it off, you can just check out the next step and you'll be all right. So after we see the state we have, we'll start to do some stuff. At the beginning, like everything it's like an UI application, and basically in the component, and we'll start to move things out of it. The first step is we'll a React hook, just like that, we are moving it out of the React hook, then we have a small break, and then actually we will move to an application. So this, I will show you a bit what is in this application I'm talking about because from step one to the step two, it's actually a lot of changes, so we'll have to see actual type and code. After that, we'll still have a refactor, and we have a few values in our application, and we will make it work, not being triggered by the UI but being triggered by something else. And then we will have some new features, so this application has one test and two features, feature flags working, and we will have more stuff on top. For example, the first feature we will implement is adding more sounds to the test, and then we will create a lobby for the application, because right now the application starts automatically. This is a game we're playing, we're making a game, a small quiz game, and the game starts automatically, so the user gets a bit confused. So what we will do is actually ask the user when you want to start, what you want to do, so we can play and start the game. And then we will have the Dan animation. We will understand who is Dan in a bit. Maybe of you, if you are fans of Mortal Kombat, you may know who is Dan. So we will create an animation similar to the Dan gentleman, and then just a small feature to change the name of the picture of the person that we're showing. You understand what I'm talking about, the bit. This was a feature required by my wife, because she was playing, she didn't like the names of the figures, and like maybe should the name that they use on the TV show. So let's see what they're going to do. Any questions so far? Good. All right.

2. Introduction to the Quiz Game

Short description:

We are building a quiz game about the friend's TV show. You don't need to know the TV show to play the game. There's a QR code for reference. If you don't know the TV show, no worries, you'll survive.

So we are building a quiz game about the friend's TV show. If you don't know them, it's okay. You don't need to know the TV show to actually play the game, but there's a QR code here and you can take a look at why those guys and why we're making a game out of them. I believe it's a very famous TV show. Does anyone here that doesn't know this TV show? Please raise your hand. No? Anyone that knows this, make sure that you'll listen. There's a feature on Zoom that actually raises the hand if you use it. You just pop the top so I can see if you have the camera off. Good. Thank you, José. Anyone that doesn't know? Okay. It's okay. You'll survive. No worries.

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