Conditional Rendering | Mastering React: An In-Depth Zero to Hero Video Series

Summary

In this React JS tutorial, the instructor guides beginners through conditional rendering, a core concept for displaying different UI elements based on state. The video demonstrates using if-else, switch-case, ternary operators, and logical AND for conditional rendering. It also covers dynamically changing class names for active buttons, showcasing efficient ways to manage UI states and styles. The instructor concludes with a challenge to build a navigation system with conditional content display, encouraging hands-on learning.

Takeaways

• 🎓 This video is part of a React JS tutorial series aimed at beginners.
• 📝 The script explains how to implement conditional rendering in React applications.
• 🔧 The tutorial demonstrates using state to control the display of different JSX elements based on conditions.
• 🔄 It showcases changing the state by clicking buttons to toggle between 'red box' and 'green box' display.
• 📚 The video introduces different methods for conditional rendering, including if-else, switch-case, ternary operators, and logical AND operators.
• 🛠️ A practical example is given where the border color of buttons changes based on their active state.
• 👨‍🏫 The script provides a step-by-step guide on how to apply conditional class names to elements.
• 📝 The presenter suggests an exercise for viewers to create a navigation system with conditional content display.
• 🔗 A Git repository link is provided for accessing the solution code for the tutorial.
• 👍 The video concludes with a call to action for viewers to like, subscribe, and support the channel.

Q & A

What is the main focus of the 'React JS - Zero to Hero' series?

The main focus of the 'React JS - Zero to Hero' series is to teach beginners how to learn React JS from scratch.

What was the topic covered in the previous video of the series?

The previous video covered how to render lists in React.

What is conditional rendering in React?

Conditional rendering in React refers to the ability to render different markup based on different conditions.

How does the tutorial demonstrate conditional rendering?

The tutorial demonstrates conditional rendering by creating a component with two buttons that change the state, which in turn controls the display of two divs with different classes.

What are the different methods shown for conditional rendering in the video?

The video shows conditional rendering using simple if-else statements, switch-case, ternary operators, and logical AND operators.

How does the tutorial handle changing the border color of buttons based on their active state?

The tutorial handles changing the border color by applying an 'active' class to the buttons based on their state, and using conditional rendering to apply this class.

What is the advantage of using a ternary operator over a function for conditional rendering?

Using a ternary operator allows for direct inline conditional rendering without the need for a separate function, which can simplify the code.

How can you apply multiple classes to an element with some being conditional and others always present?

You can use a ternary statement inside a template literal to apply multiple classes, where some are conditional and others are always present.

What task does the tutorial assign to the viewers?

The tutorial assigns a task to create a navigation system where clicking on a link shows corresponding content and highlights the active tab.

Where can viewers find the solution code for the tutorial?

Viewers can find the solution code for the tutorial in the GitHub repository linked in the video description.

Outlines

00:00

🛠️ Introduction to Conditional Rendering in React

This paragraph introduces the concept of conditional rendering in React, aimed at beginners learning React JS from scratch. The speaker explains how to display different components based on conditions using a new React application as an example. In this application, a component with two buttons and a state variable 'box color' is created. The state controls the display of two divs with different classes ('red box' and 'green box'). The speaker demonstrates how to use conditional rendering to show different JSX elements based on the state value, employing methods like simple if-else, switch case, ternary operator, and logical AND operator. Additionally, the paragraph discusses how to dynamically change the border color of buttons based on their active state.

05:27

🔧 Advanced Techniques for Conditional Class Names and Task Assignment

The second paragraph delves into more advanced techniques for conditional rendering, specifically focusing on conditional class names for buttons. The speaker shows how to apply an 'active' class to buttons based on their active state, initially using a more verbose approach and then simplifying it with a ternary operator. The paragraph also introduces a more efficient method using a ternary statement inside a template literal for handling multiple classes. The speaker concludes by assigning a task to the viewers to create a navigation system with conditional content display and active tab highlighting. They encourage viewers to try the task and provide a GitHub link for solution code, ending with a call to action for likes, subscriptions, and support.

Keywords

💡React JS

React JS is a popular open-source JavaScript library used for building user interfaces, particularly for single-page applications. It is maintained by Facebook and a community of individual developers and companies. In the context of the video, React JS is the main theme as the series is designed to teach beginners how to use React JS from scratch, including concepts like rendering lists and conditional rendering.

💡Conditional Rendering

Conditional rendering refers to the ability to dynamically display different components or JSX elements based on certain conditions. It is a core concept in React JS that allows developers to control the flow of the UI by showing or hiding elements. In the video, the instructor demonstrates how to use conditional rendering to display different 'div' elements based on the state of a 'box color' variable.

💡State

In React, state is an object that holds information about the component and can change over time. It is used to record and react to user interactions, network responses, and other events. The video explains how to use state to control the display of elements, such as changing the color of a box based on user interaction with buttons.

💡JSX

JSX is a syntax extension for ECMAScript (JavaScript) that looks similar to HTML and is used in React to describe the structure of the UI. It allows developers to write elements and components in a way that resembles HTML but is actually valid JavaScript. The video uses JSX to define the structure of the components that are conditionally rendered based on the state.

💡Component

A component in React is a reusable piece of code that can be used to build the UI. Components can be class-based or function-based and can have their own state and props. The video script mentions creating a new component that is used within the App component to demonstrate conditional rendering.

💡Class Name

In the context of CSS and React, a class name is used to apply styles to HTML elements. The video discusses how to conditionally apply class names to elements, such as changing the border color of a button based on its active state, which is determined by the state of the application.

💡Ternary Operator

The ternary operator is a shorthand for an if-else statement in many programming languages, including JavaScript. It is used to perform a quick inline conditional check. In the video, the ternary operator is used to conditionally render different JSX elements and to apply class names based on the state of the application.

💡Logical AND Operator

The logical AND operator is used to combine multiple conditions in a statement. In the context of the video, it is used to conditionally render elements by returning them only when all conditions are true, which is a more concise way to write conditional rendering compared to using if-else or switch-case.

💡CSS Styles

CSS (Cascading Style Sheets) is used to style the HTML elements in a web application. The video mentions adding CSS styles to classes like 'red box' and 'green box' to visually differentiate them. CSS is crucial for making the conditional rendering visually apparent to the user.

💡Navigation

Navigation in web development refers to the process of moving between different pages or sections of an application. The video ends with a task for viewers to create a navigation system where clicking on different links shows different content, and the active tab is highlighted. This demonstrates how conditional rendering can be applied to build interactive UIs.

Highlights

Introduction to conditional rendering in React JS for beginners.

Explanation of conditional rendering to display different markups based on conditions.

Demonstration of a new React application with a component for conditional rendering.

Use of state 'box color' to manage the display of different colored boxes.

Implementation of two buttons to change the 'box color' state.

Display of two divs with 'red box' and 'green box' classes.

CSS styling applied to 'red box' and 'green box' classes for visual differentiation.

Conditional rendering of boxes based on the 'box color' state.

Introduction to using an if-else approach for conditional rendering.

Switching to a switch case for conditional rendering.

Utilization of a ternary operator for concise conditional rendering.

Direct use of ternary operator within JSX for simplicity.

Using the logical AND operator for rendering elements conditionally.

Adding a 2px border to buttons and changing border color for the active button.

Applying the 'active' class conditionally to buttons based on the 'box color' state.

Optimization of class name assignment using ternary operator for active buttons.

Simplification of class name management with ternary statements inside template literals.

Task assignment for creating a navigation system with conditional content display.

Highlighting of the active tab in the navigation system.

Invitation to subscribe and support the channel for further learning.

Transcripts

Hi Friends

Welcome back to React JS - Zero to Hero series.

This series is for beginners who wants to learn React JS from Scratch.

In the last video I have explained about how we can render lists in react and in this video,

I am going to explain about conditional rendering in react.

Let's start.

We may need to display different things depending on different conditions.

Conditional rendering is a term to describe the ability to render different markups based

on different condition.

To explain this, I have created a new react application in which I have created a component

and I am using that in the App component.

In this component, I have created two buttons.

And I am having a state called box color and I am defaulting that to red and on clicking

these buttons I am changing the state.

And I have created two divs.

First one is having the class as red box and the second one is having green box.

I have already added some css styles to these classes and so, we can see this.

Now, both the boxes are displaying.

But I want to display the red box and on clicking the green button I need to hide the red box

and show the green box.

That means, based on the state value, we are going to display different JSX elements.

This is conditional rendering.

Let's see how we can do that.

First let's try a simple if else approach.

For that, let me create a new function.

Inside this function, if box color is equal to red, let me return this JSX and otherwise

let me return this JSX.

And, let me call this function here.

And so, initially red box is displayed and if I click green button, we can see the green

box.

Similar to if else, we can also use switch case.

Let me quickly comment this and rewrite to a switch case.

And so, we can see this is also working.

Now, let me use a ternary operator.

Like this.

And we can see, this is also working.

And another advantage of going for ternary operator is, instead of having this inside

a function and call that function here, we can directly use the ternary operator here.

Like this.

This will also work.

Also, instead of this, we can split this and render like this.

We can see this is also working.

And even shorter, we can use the logical AND operator to render like this.

This will also work.

Ok.

Let's add one more requirement to this.

Let me add a 2px border to these buttons.

Now, I want to change the border color to blue for the active button.

Initially red button is active and so it should have the blue border and when I click green

button, that should have the blue color border.

For that, let me add a class called active and let me change the border color inside

that class.

Now, we need to find a way to apply this class name to the active button.

Actually, we can follow the same approach like how we rendered these boxes divs conditionally.

So let me copy this and paste it here and let me cut this and paste inside both the

conditions.

For the first one, let me add the active class name here and for the second one let me add

that here.

Now, we can see the blue border in the red button.

When I click the green button, it is getting the blue border.

So, it is working.

But this approach is little lengthy.

I don't like this approach.

Let me show you another approach.

Let me copy these buttons.

And, instead of hardcoding the active class name, I can use ternary operator and show

the active class name if the condition matches, otherwise I can simply use null.

Like this.

Let me do the same for the other button as well.

Now, we can see it is working, but this time we are not conditionally rendering the entire

button element, we are conditionally changing the class name only.

Ok, now let me add another class and add some css to that.

I wanted to have that class always regardless of the condition.

So, I can use it like this instead of null.

But the problem here is, if the number of classes I wanted to show always is more and

I want to show few classes based on condition, then we need to rewrite all these classes

in both the conditions of the ternary operator.

Instead, we can use a ternary statement inside a template literal.

Like this.

This will also work.

This is the simplest approach.

Hope you understood how you can conditionally render elements and class names.

Let me give you a task.

You can create a navigation like this.

When this link is clicked, this content should be shown.

If this link is clicked, we have to show this content.

Also, please note that the active tab is also highlighted.

Try this.

If you need the solution code, you can take it from this Git repo.

The link is available in the description.

That's all for today.

Please like this video.

Subscribe my channel and support me.

Thank you.

Bye.