Components | Mastering React: An In-Depth Zero to Hero Video Series
Summary
TLDRIn this React JS tutorial, the instructor introduces components, the building blocks of React applications, highlighting their reusability. The video explains the difference between functional (stateless) and class (stateful) components. It covers the basics of creating both types, with a focus on the shift towards functional components post-React 16.8 due to Hooks. The instructor demonstrates creating a class component and emphasizes reusability by refactoring an App component and introducing a Student component. The video concludes with a task for viewers to build an application with header, top nav, main, and footer components, and encourages practice with a provided GitHub solution.
Takeaways
- đ This video is part of a 'React JS - Zero to Hero' series aimed at beginners learning React JS from scratch.
- đ The script follows up from a previous discussion on JSX and introduces the concept of components in React.
- đ Components in React are isolated pieces of UI with their own logic and appearance, emphasizing reusability.
- 𧩠There are two types of components in React: Functional Components (Stateless) and Class Components (Stateful).
- đ€ Functional components are simple JavaScript functions returning JSX, without a render method and no lifecycle methods.
- đ Class components are ES6 classes extending React.Component, featuring a render() method and lifecycle phases.
- đ The introduction of React Hooks in version 16.8 has led to a preference for functional components over class components.
- đ Despite the shift, understanding class components is essential due to their presence in legacy applications.
- đ The video demonstrates creating a class component by extending React.Component and using it within an App component.
- đ The script highlights component reusability by showing how to create and reuse a Student functional component.
- đ The presenter suggests a practice task involving creating a header, top nav, main, and footer component, all reusable within an App component.
Q & A
What are the two main types of components in React?
-The two main types of components in React are Functional Components, also known as Stateless components, and Class Components, also known as Stateful components.
What is the primary advantage of using components in React?
-The primary advantage of using components in React is reusability, which allows developers to create isolated pieces of UI that can be used multiple times across the application.
How are functional components defined in React?
-Functional components in React are typically defined using arrow functions, but they can also be created with the regular function keyword. They are simple JavaScript functions that return JSX.
Why are functional components referred to as 'stateless'?
-Functional components are referred to as 'stateless' because they do not have their own state and simply accept data and return JSX based on that data.
What is a Class Component in React and how is it different from a Functional Component?
-A Class Component in React is a regular ES6 class that extends the Component class from the React library. It is different from a Functional Component in that it can have its own state and lifecycle methods, and it must implement a render() method that returns JSX.
What is the significance of React Hooks introduced in React 16.8?
-React Hooks, introduced in React 16.8, allow developers to use state and other React features in functional components, which has led to a preference for functional components over class components for most use cases.
Why is it important to understand Class Components even though they are less commonly used now?
-It is important to understand Class Components because some legacy applications still use them, and having this knowledge can be helpful for maintaining and updating existing codebases.
How do you create a Class Component in React?
-To create a Class Component in React, you define a class that extends React.Component, ensure the component's name starts with an uppercase letter, implement a render() method that returns JSX, and export the component for use in other parts of the application.
What is the benefit of creating separate files for components in a React application?
-Creating separate files for components in a React application helps in organizing the code better, making it more maintainable and readable, and allows for easier reuse of components.
How can you demonstrate the reusability of components in React?
-The reusability of components in React can be demonstrated by creating a component once and then using it multiple times in different parts of the application or even multiple times within the same section of the UI.
What is the next topic the video series will cover after explaining components?
-The next topic the video series will cover is passing values dynamically to components, which is essential for creating more flexible and interactive React applications.
Outlines
đ Introduction to React Components
This paragraph introduces the concept of components in React, which are isolated pieces of UI with their own logic and appearance. The paragraph explains the two main types of components in React: Functional Components (also known as Stateless components) and Class Components (also known as Stateful components). Functional components are simple JavaScript functions that return JSX and do not have a render method or lifecycle methods, as they are plain JavaScript functions. Class components, on the other hand, are ES6 classes that extend the React component class and must implement a render() method. They also have lifecycle methods associated with different phases such as Mounting, Updating, Unmounting, and Error Handling. The paragraph also discusses the shift towards functional components with the introduction of React Hooks in version 16.8, which has led to a decline in the use of class components. The instructor demonstrates how to create a class component by extending the React component class, implementing a render method, and exporting it for use in other components. The paragraph concludes with a brief mention of the reusability of components, which will be further explained in the next video.
đ Demonstrating Component Reusability
The second paragraph focuses on the reusability of components in React applications. The instructor creates a new functional component called 'Student' using an arrow function and demonstrates how it can be reused multiple times within the 'App' component. This showcases the practical application of component reusability, which is a key advantage of using components in React. The paragraph also hints at future topics, such as passing values dynamically to components, which will be covered in the next video. The instructor concludes by assigning a small task for the viewers to create an application with various components like a header, top nav, main, and footer, and encourages them to style these components using inline styles. The task is designed to help viewers practice what they've learned about components. The paragraph ends with a call to action for viewers to like, subscribe, and support the channel.
Mindmap
Keywords
đĄReact JS
đĄJSX
đĄComponents
đĄFunctional Components
đĄClass Components
đĄReusability
đĄLifecycle Methods
đĄReact Hooks
đĄState
đĄProps
đĄEvent Handling
Highlights
Introduction to React JS for beginners, focusing on building UI from components.
Explanation of components as isolated pieces of UI with their own logic and appearance.
Advantage of components in React is their reusability.
Differentiation between Functional Components and Class Components.
Functional components are simple JavaScript functions returning JSX.
Functional components are stateless and do not use a render method.
Class components extend the Component class from the React library and are stateful.
Class components must have a render() method that returns JSX.
Lifecycle methods in class components include Mounting, Updating, Unmounting, and Error Handling.
React Hooks introduced in React 16.8, leading to a preference for functional components.
Class components may become deprecated, but understanding them is still necessary for legacy applications.
Step-by-step guide on creating a class component, including naming conventions and importing React.
Demonstration of rendering a class component in the UI.
Introduction to functional components using arrow functions and JSX.
Example of reusing a functional component multiple times in the UI.
Teaching how to pass values dynamically to components, to be covered in the next video.
Assignment for viewers to create an application with a header, top nav, main, and footer component.
Encouragement for viewers to try the task on their own and reference a GitHub repo for solutions.
Call to action for viewers to like, subscribe, and support the channel.
Transcripts
Hi Friends
Welcome back to React JS - Zero to Hero series. This Â
series is for beginners who wants to learn React JS from Scratch.
In the last video I have explained about JSX. In this video, Â
I am going to explain about components.
Let's start.
React applications are built from isolated pieces of UI called components. A component Â
is a piece of the user interface that has its own logic and appearance. Â
The main advantage of the component is reusability.
There are mainly two components in React. Functional Components also Â
known as Stateless component. And, Class Component also known as Stateful component.
Functional components are simple javascript functions, that returns some JSX. They are Â
also called "stateless" components because they simply accept data and render them in UI. Â
There is no render method used in functional components. Functional components can be Â
typically defined using arrow functions but can also be created with the regular function keyword. Â
Component lifecycle method do not exist in functional component, Â
because a functional component is just a plain JavaScript function.
Even in our previous videos, I have used functional components only.
Class components are regular ES6 classes that extends component class form react library. Â
They are also known as "stateful" components, because they implement logic and state. Â
It must have a render() method that returns JSX. There are 4 component lifecycle phases available Â
in class components. They are Mounting, Updating, Unmounting and Error Handling. Â
And, in each phase we have different component lifecycle methods like componentDidMount, Â
compondentDidUpdate, componentWillUnmount, etc.
Earlier, react developers prefer to use class components to create stateful components Â
and functional components to create stateless components. Before React 16.8, Class components Â
were the only way to track state and lifecycle on a React component. But, in React version 16.8, Â
React Hooks got introduced. After the introduction of Hooks, most of the developers prefer to use Â
functional components for everything. So, now-a-days class components are dying slowly. Â
In future, those may get deprecated. But I think there is no official announcement about that.
But still, you need to have an understanding on class components, Â
because some of the legacy applications are still having class components.
So, let me explain how we can create a class component.
First let me create a javascript file. Â
Inside that, I need to have a class that should extend react dot component. Â
When creating a React component, the component's name must start Â
with an upper case letter. And, we need to import the react library.
And, the component also requires a render() method, this method returns JSX. Â
Finally, let me export this component, so that I can use it in other components.
Now, let me go to the index dot js. And, use the class component there.
So, we can see our class component is rendering in the UI.
This is how we can create a class component.
The way we call the events, maintain the state and props, lifecycle methods, Â
and other concepts differ between functional and class components. If I explain both, it Â
may confuse you. It takes lot of time to explain the same concept in both the components. Also, Â
as most of the react developers are moving towards functional components, I am going to mostly use Â
only functional components in the upcoming videos. And, use class components where ever needed.
And, I have told the main advantage Â
of the component in react is its reusability. Let me explain that.
First, let's do some cleanup. In index dot js, we have the App function. Â
Let's move this App function or App component to a separate file. For that, let me create a Â
App dot js file. And, let me move this function there. Let me also move these imports. And, Â
let me export this App component. In index dot js, let me import the App component. Â
I need to move this function also to App component, because we are using this there only.
Now, our app is still working. But our index dot js is clean.
Ok. Let me create a new functional component called Student. This time I am Â
going to use arrow function instead of normal function. And, let me return some JSX inside.
And, I am going to show this component inside our App component.
So, we can see our student component is showing in the UI. Assume, you want Â
to use the same component in different places, we can simply use this component. Â
Even here, if I want to show it two more times, I can simply reuse. Like this.
Now, we can see 3 students are showing. This is what I was telling about reusability.
Ok. Here we are hardcoding some values. But it will be nice, if we are able to Â
pass these values dynamically. That is what I am going to explain in the next video.
And, let me explain a small task and you can try that. You can create an application like this, Â
in which you need to create a header component, a top nav component, a main component and a Â
footer component. You can use inline styles to style your components. And, you can use Â
all your components inside App component. So that, it should appear similar to this.
Try it on your own. In case you need to see the solution, Â
you can get it from this github repo. The link is also in the description.
That's all for today.
Please like this video. Subscribe my channel and support me.
Thank you. Bye.
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