What is React | Lecture 09 | React.JS 🔥

Summary

React, a popular JavaScript library created by Facebook, is known for building user interfaces through a component-based design. It utilizes JSX, a declarative syntax, to describe components and keep the UI in sync with state changes. React's state-driven nature allows it to automatically re-render the UI, reflecting the latest state. Despite being a library, not a full framework, it has spawned frameworks like Next.js and Remix. Its widespread adoption by major companies and a thriving community make React a sought-after skill in the job market, with a rich ecosystem of third-party libraries and tools.

Takeaways

• 📚 React is a JavaScript library for building user interfaces, originally created by Facebook.
• 🧱 It is a component-based design system, where components like buttons and input fields are the building blocks of UIs.
• 🔄 Components can be reused and combined, similar to LEGO pieces, to construct complex user interfaces.
• 📈 React utilizes JSX, a declarative syntax that combines HTML, CSS, and JavaScript, to describe components and UIs.
• 🌐 React abstracts the DOM, allowing developers to focus on what should happen rather than how to implement it.
• 🔄 State-driven: React keeps the UI in sync with the current state, re-rendering the UI when state changes.
• 📊 React is extremely popular, with the highest weekly download numbers among similar frameworks, indicating a strong job market for React developers.
• 🌐 A large and active React developer community provides extensive support, tutorials, and a wealth of third-party libraries.
• 🛠️ React is not a full-fledged framework but a library; complete applications often use additional libraries like Next.js or Remix.
• 🏢 Created by Facebook in 2011 and open-sourced in 2013, React has been adopted by many large companies and has influenced the development of other modern frameworks.

Q & A

What is React according to the official documentation?

According to the official documentation, React is a JavaScript library for building user interfaces.

How can the definition of React be extended to be more helpful?

React can be described as an extremely popular, declarative, component-based, state-driven JavaScript library for building user interfaces, created by Facebook.

What does component-based design mean in React?

Component-based design in React means that the user interface is built using components such as buttons, input fields, and search bars, which are the building blocks and can be combined like LEGO pieces to create complex UIs.

How does React facilitate the reusability of components?

React allows components to be reused by creating them once and then using them multiple times with slightly adjusted data, as seen in the example of a listing component reused in a results panel.

What is JSX and how is it used in React?

JSX is a special declarative syntax used in React that combines parts of HTML, CSS, and JavaScript. It allows developers to describe what components should look like and how they work based on the current state.

How does React differ from working directly with the DOM in vanilla JavaScript?

React abstracts the DOM, so developers never have to work with the DOM directly. Instead, they tell React what they want to happen when data changes, without specifying how to do it.

What is the role of state in updating the UI in React?

State in React is the data that keeps the UI in sync. When the state changes, React automatically re-renders the user interface to reflect the latest state, effectively reacting to state changes.

Is React a framework or just a library?

React is actually just a library, not a full-fledged framework. It represents the view layer, and to build a complete application, developers need to integrate multiple external libraries for functionalities like routing and data fetching.

Why is React so popular among developers and companies?

React is popular because it is backed by Facebook (now Meta), has a large and active developer community, offers high demand for qualified developers in the job market, and has a vast third-party library ecosystem.

Who created React and when was it first used?

React was created in 2011 by Jordan Walke, an engineer at Facebook. It was first used on Facebook's newsfeed and chat app, and later open-sourced in 2013.

What are some of the techniques employed by React to keep the UI in sync with state?

React uses techniques such as a virtual DOM, a Fiber tree, and one-way data flow to efficiently update the UI in response to state changes.

Outlines

00:00

🌟 Introduction to React and its Fundamentals

This paragraph introduces the viewer to React, the most popular JavaScript framework for building user interfaces. It explains that React is a library created by Facebook and emphasizes its declarative, component-based, and state-driven nature. The lecture aims to provide a high-level overview of React, discussing its components as building blocks for UIs and the use of JSX for describing components' appearance and behavior. The concept of re-rendering the UI in response to state changes is introduced, highlighting React's efficiency in updating the interface without direct DOM manipulation. The paragraph also touches on the debate over whether React is a framework or a library, clarifying that it is, in fact, a library focused on the view layer.

05:01

🚀 The Popularity and Ecosystem of React

This paragraph delves into the reasons behind React's widespread adoption, highlighting its position as the most used framework according to npm download numbers. It discusses the support from large companies and the resulting job market for React developers, which is characterized by high demand and well-paying positions. The paragraph also mentions the active global React community, which contributes to a wealth of tutorials, Q&A on platforms like Stack Overflow, and third-party libraries. The historical context of React's creation by Jordan Walke at Facebook in 2011 and its subsequent open-sourcing in 2013 is provided. The paragraph concludes by summarizing React's strengths in rendering components and maintaining UI-state synchronization, and mentions the technical concepts like the virtual DOM and one-way data flow that will be studied in the course.

Keywords

💡JavaScript Framework

A JavaScript Framework is a structured approach to building web applications using JavaScript. It provides a set of pre-written code, components, and tools that streamline the development process, making it easier to create complex and scalable user interfaces. In the context of the video, React is introduced as a popular JavaScript framework developed by Facebook, emphasizing its role in modern front-end web development.

💡React

React is an open-source JavaScript library created by Facebook, primarily used for building user interfaces. It is known for its component-based architecture, which allows developers to build reusable UI components. React also employs a virtual DOM to improve performance by limiting real DOM manipulations, and it uses a unidirectional data flow to keep the UI in sync with the underlying data state.

💡User Interfaces

User Interfaces (UIs) are the visual and interactive elements through which users interact with a website or application. In the context of React, UIs are built using components that represent different parts of the interface, such as buttons, input fields, and navigation bars. React's approach to UI construction emphasizes modularity and reusability, which simplifies the process of creating complex and dynamic interfaces.

💡Components

In React, components are the fundamental building blocks of a UI. They are individual, reusable pieces of the interface that encapsulate their own state, props, and logic. Components can be as simple as a button or as complex as an entire application feature. They can also include other components, creating a hierarchical structure that mirrors the structure of the UI.

💡JSX

JSX, or JavaScript XML, is a syntax extension for JavaScript that allows developers to write HTML-like code within their JavaScript code. In React, JSX is used to describe the structure and appearance of UI components in a declarative manner. It combines elements of HTML, CSS, and JavaScript, and it can reference other React components, making the code more readable and easier to maintain.

💡State

In React, state refers to a component's dynamic data that can change over time. It is an object that stores information relevant to the component's behavior and appearance. When the state changes, React automatically re-renders the component and its children to reflect the updated data. This mechanism ensures that the UI remains in sync with the underlying data, providing a responsive and interactive user experience.

💡Virtual DOM

The Virtual DOM is a representation of the actual DOM, but in a form that React can efficiently update. Instead of directly manipulating the real DOM, which can be slow, React uses the Virtual DOM to determine the changes needed and applies them in the most efficient way. This process is often referred to as 'diffing' and results in faster and smoother UI updates.

💡Declarative

In programming, declarative code is a way of specifying the desired outcome without explicitly stating how to achieve it. In the context of React, declarative programming is used to define UI components by describing what they should look like based on the current state, rather than how to manipulate the DOM to achieve that appearance. This approach simplifies the development process and makes the code more predictable and easier to maintain.

💡Reusability

Reusability in software development refers to the ability to use a piece of code or a component in multiple places or contexts without the need for significant modification. In React, components are designed to be reusable, allowing developers to create modular UI elements that can be easily integrated into different parts of an application. This enhances productivity and maintainability by reducing redundancy and encouraging a more efficient development process.

💡Community

A community in the context of software development refers to a group of users, developers, and contributors who share knowledge, resources, and support related to a particular technology or platform. The React community is highlighted in the video as a significant factor in its popularity and success, providing extensive resources, tutorials, and support for developers, which in turn fosters a thriving ecosystem of third-party libraries and tools.

💡Facebook/Meta

Facebook, now known as Meta, is the parent company of React. The company not only created React but also continues to maintain and develop it. The association with Facebook gives React credibility and resources, and it was initially used within Facebook's products before being open-sourced. The video mentions that React was created by Jordan Walke, an engineer at Facebook, and has since been adopted by many other companies and projects.

Highlights

React is an extremely popular, declarative, component-based, state-driven JavaScript library for building user interfaces, created by Facebook.

Components are the building blocks of user interfaces in React, such as buttons, input fields, search bars, etc.

React allows the creation of complex UIs by combining multiple components, similar to LEGO pieces.

Components can be reused, which promotes efficiency and maintainability in UI development.

JSX is a declarative syntax used in React to describe what components should look like based on the current state.

React abstracts the DOM, meaning developers do not have to work with the DOM directly.

React's main goal is to keep the UI in sync with data, which is referred to as state.

React automatically re-renders the UI to reflect the latest state when state changes occur.

React is often debated whether it is a framework or just a library; it is technically a library focused on the view layer.

Frameworks built on top of React, like Next.js and Remix, provide additional functionalities for complete application development.

React's popularity is reflected in its high weekly download numbers from npm, making it the most used framework.

Large companies have adopted React, leading to a high demand for qualified React developers in the job market.

React's popularity has fostered a large and active developer community, providing extensive support and resources.

A vast third-party library ecosystem has grown around React due to its large community.

React was created by Facebook in 2011 and was open-sourced in 2013.

React has transformed front-end web development and inspired the creation of many other modern frameworks.

React is good at rendering components on a webpage based on their current state and keeping the UI in sync with state changes.

Techniques like the virtual DOM, Fiber tree, and one-way data flow are employed by React for efficient UI updates.

Transcripts

‫So now that we know

‫why we need a JavaScript framework in the first place,

‫let's start by learning about the most popular framework

‫out there, React.

‫So in this lecture, we will get a high-level overview

‫of what React actually is and how it works.

‫So it's gonna be a full packed

‫but super interesting lecture.

‫So let's quickly get started.

‫So according to the official React documentation,

‫React is a JavaScript library for building user interfaces.

‫Now, that's something

‫but it really isn't that helpful, is it?

‫So let's extend this definition by a bit

‫so that it becomes more helpful

‫or, should I say, a little bit more crazy like this.

‫So now, in this slightly modified definition,

‫React is an extremely popular, declarative,

‫component-based, state-driven,

‫JavaScript library for building user interfaces,

‫created by Facebook.

‫And this is actually a lot more helpful

‫because now, we can deconstruct this definition

‫and learn about what React actually is, step by step.

‫So starting with component-based design,

‫React is all about components such as buttons,

‫input fields, search bars, and so on.

‫So components are the building blocks of user interfaces

‫in React.

‫And in fact, basically all React does

‫is to take components and draw them on a webpage.

‫That's it.

‫And so we built complex UIs in React

‫by building multiple components

‫and then combining these components like LEGO pieces.

‫For example, to create a complex application like Airbnb.

‫So here we have exactly the same components

‫that we saw earlier, but all combined into a complex UI.

‫So the navbar, the search bar,

‫the results panel, and the map.

‫Now, another thing that we do with components

‫is to reuse them.

‫For example, here in the results panel,

‫there are multiple listing that look quite similar.

‫And so we can create a listing component

‫and then reuse it three times here,

‫simply adjusting the data a little bit.

‫Now, since we built complex UIs

‫by combining multiple components,

‫each component must have all the information

‫about what it looks like, right?

‫So in order to describe what each component looks like

‫and how it works,

‫we use a special declarative syntax called JSX.

‫And declarative simply means

‫that we tell React what a component

‫and ultimately the entire UI should look like

‫based on the current state.

‫So React is basically a huge abstraction away from the DOM

‫so that we never have to work with a DOM directly

‫as we would with vanilla JavaScript.

‫So we simply tell React what we want to happen

‫when some data changes, but not how to do it.

‫And again, we do that using JSX.

‫So JSX is basically a syntax that combines parts of HTML,

‫CSS, JavaScript, and it even allows us

‫to reference other React components.

‫And the declarative nature of React

‫is an essential concept that, of course,

‫we will really dive into later.

‫But now you might wonder, if we never touch the DOM,

‫then how does React update the UI?

‫Well, that's where the concept of state comes into play.

‫So remember that the main goal of React

‫is to always keep the UI in sync with data.

‫And from now on, let's actually call that data, state.

‫For example, an array of apartments on Airbnb.

‫So based on our initial state,

‫React will render a user interface

‫using the components that we wrote using JSX.

‫Then based on some event like a button click,

‫the state might change.

‫For example, more data about apartments

‫might be loaded from an API.

‫And so here comes the interesting part.

‫Whenever the state changes,

‫we manually update the state in our app

‫and React will then automatically

‫re-render the user interface to reflect that latest state,

‫or in other words,

‫React react to state changes by re-rendering the UI.

‫And that is in fact the whole reason

‫why React is called React in the first place.

‫Now, there's always been some debate

‫over whether React is actually a framework

‫or just a library.

‫Well, the short answer is that React

‫is actually just a library,

‫even though I keep calling it a framework.

‫And the reason for that is that React itself

‫is really only the so-called view layer.

‫So if we want to build a complete real world application,

‫we need to choose multiple external libraries

‫to add to our project.

‫For example, for routing or for data fetching.

‫Now to address this, there are actually multiple frameworks

‫that have been built on top of React.

‫So frameworks that include all these functionalities

‫that React is missing out of the box,

‫and the most popular ones are called Next.js and Remix.

‫But again, more about all that later in the course.

‫Now, moving on.

‫Besides all the great features

‫that we've been talking about,

‫maybe the biggest reason to choose React

‫over all the other frameworks that are similar

‫is because React is extremely popular.

‫So according to the weekly download numbers from npm,

‫React is by far the most used framework.

‫And the difference between React and the other ones

‫only seems to be growing.

‫So React really isn't going anywhere.

‫A big reason for that is that many large companies

‫have adopted React a long time ago.

‫And so now, more and more smaller companies

‫all over the world are following in their footsteps.

‫This means that all these companies

‫now need React developers for their teams,

‫which, of course, has created a huge worldwide job market

‫with a high demand for qualified React developers.

‫And these are not just any jobs.

‫They're usually well-paying jobs.

‫Now, even another positive outcome

‫of React's huge popularity is that now,

‫there is a very large and active React developer community,

‫which means that there are always gonna be

‫lots of tutorials, Stack Overflow questions and answers,

‫and also lots of support given to other React developers.

‫And if you ask me,

‫this is actually one of the strongest benefits

‫of using React right now.

‫Also because this huge community has grown

‫a truly gigantic third-party library ecosystem around React.

‫And so now, you can integrate countless useful libraries

‫and tools into your own React applications.

‫And now, our last topic

‫is that React was created by Facebook.

‫Well, more specifically,

‫React was created in 2011 by Jordan Walke,

‫who is an engineer who was working at Facebook at the time.

‫So that's why we say that React is backed by Facebook

‫or now, by Meta.

‫So there, React was first used on the newsfeed

‫and also the chat app.

‫And from there, it spread out to the entire Facebook

‫and also the Instagram applications.

‫Then in 2013, React was open-sourced for everyone to use it

‫and the rest is history

‫because React has truly and completely transformed

‫front-end web development,

‫not only by developers that are using React itself,

‫but because many other modern frameworks

‫were created as a response,

‫which really changed the industry forever.

‫Okay, so to summarize, React is really good at two things.

‫First, rendering components on a webpage

‫as a user interface based on their current state.

‫And second, React is really good

‫at keeping the user interface in sync with state

‫by re-rendering, or in other words, by reacting

‫when the state of one of the component changes.

‫And as you will see later, React does all this

‫by employing something called a virtual DOM,

‫a Fiber tree, one-way data flow,

‫and many other techniques that we will study

‫throughout this course.

‫All right.

‫And so now that you have a rough overview

‫of what React actually is,

‫let's set up our development environment

‫so that we can start writing some serious code finally.