Learn React step by step in this beginner-friendly course, mastering components, hooks, and routing to build dynamic and scalable web applications.

React is a popular library for building modern web applications, known for its efficiency and simplicity. This course will help you understand React’s core features, like components, hooks, and routing, to create dynamic, scalable, and user-friendly applications. Whether new to React or enhancing your skills, this course offers a structured approach to building React-based projects.

After a quick refresher on JavaScript fundamentals, you’ll explore React concepts such as component-based architecture, JSX syntax, state management using hooks, and navigation with React Router. With interactive coding examples, practice exercises, and chapter-end challenges, you’ll reinforce your learning through hands-on experience.

By the end of this course, you’ll have the confidence and necessary skills to create practical web applications with React and pursue advanced topics in React development.

Learn React

It directly modifies the real DOM for faster updates.

It eliminates the need for JavaScript in UI updates.

It minimizes real DOM updates by identifying changes.

What is the primary advantage of React’s virtual DOM?

<p>What is the primary advantage of React’s virtual DOM?</p>


<p>What is <em>not</em> a feature of React?</p>


`ReactDOM.render` is used inside `createRoot`.

`createRoot` is used to render JSX directly into a DOM node.

`createRoot` creates a root container, and its `render` method renders JSX into the DOM.

`createRoot` directly replaces the real DOM with React elements.

Which statement is correct for rendering JSX using `createRoot`?

<p>Which statement is correct for rendering JSX using <code>createRoot</code>?</p>


JSX can include multiple root elements in a single return statement.

JSX elements must be enclosed in a parent container.

JSX does not support JavaScript expressions.

JSX must always start with a `<div>` tag.

<p>Which option is a valid JSX rule?</p>


**(True or False)** React allows dynamic updates to the DOM by embedding JavaScript expressions in JSX.

<p><strong>(True or False)</strong> React allows dynamic updates to the DOM by embedding JavaScript expressions in JSX.</p>


**(True or False)** The `createRoot` method automatically enables concurrent rendering in React.

<p><strong>(True or False)</strong> The <code>createRoot</code> method automatically enables concurrent rendering in React.</p>


**(True or False)** JSX must always start with a `<div>` as the root element.

<p><strong>(True or False)</strong> JSX must always start with a <code>&lt;div&gt;</code> as the root element.</p>


**(True or False)** The `render` method of a root container replaces the old DOM node entirely.

<p><strong>(True or False)</strong> The <code>render</code> method of a root container replaces the old DOM node entirely.</p>


**(True or False)** `ReactDOM.render` is the recommended way to render React elements in React 18 and beyond.

<p><strong>(True or False)</strong> <code>ReactDOM.render</code> is the recommended way to render React elements in React 18 and beyond.</p>


`Hello, React!` is displayed inside an `<h1>` element.

`Hello, React!` is displayed as plain text.

What is the output of the following code?
```react
import React from "react";
import { createRoot } from "react-dom/client";

const element = <h1>Hello, React!</h1>;
const root = createRoot(document.getElementById("root"));
root.render(element);
```

<p>What is the output of the following code?</p>
<pre><code class="language-react">import React from &quot;react&quot;;
import { createRoot } from &quot;react-dom/client&quot;;

const element = &lt;h1&gt;Hello, React!&lt;/h1&gt;;
const root = createRoot(document.getElementById(&quot;root&quot;));
root.render(element);
</code></pre>


What does the following code render?
```react
const root = createRoot(document.getElementById("root"));
root.render(<p>{5 + 5}</p>);
```

<p>What does the following code render?</p>
<pre><code class="language-react">const root = createRoot(document.getElementById(&quot;root&quot;));
root.render(&lt;p&gt;{5 + 5}&lt;/p&gt;);
</code></pre>


A paragraph with the hobbies listed as plain text.

An unordered list with two items: `Reading` and `Gaming`.

An error due to missing the `key` attribute.

What is rendered by the following JSX?
```react
const hobbies = ["Reading", "Gaming"];
const element = (
  <ul>
    {hobbies.map((hobby) => (
      <li key={hobby}>{hobby}</li>
    ))}
  </ul>
);
const root = createRoot(document.getElementById("root"));
root.render(element);
```

<p>What is rendered by the following JSX?</p>
<pre><code class="language-react">const hobbies = [&quot;Reading&quot;, &quot;Gaming&quot;];
const element = (
  &lt;ul&gt;
    {hobbies.map((hobby) =&gt; (
      &lt;li key={hobby}&gt;{hobby}&lt;/li&gt;
    ))}
  &lt;/ul&gt;
);
const root = createRoot(document.getElementById(&quot;root&quot;));
root.render(element);
</code></pre>


A `div` containing `Alice` and `25` as plain text.

A `div` containing an `h1` with `Alice` and a `p` with `Age: 25`.

What is the result of this code?
```react
const user = { name: "Alice", age: 25 };
const element = (
  <div>
    <h1>{user.name}</h1>
    <p>Age: {user.age}</p>
  </div>
);
const root = createRoot(document.getElementById("root"));
root.render(element);
```

<p>What is the result of this code?</p>
<pre><code class="language-react">const user = { name: &quot;Alice&quot;, age: 25 };
const element = (
  &lt;div&gt;
    &lt;h1&gt;{user.name}&lt;/h1&gt;
    &lt;p&gt;Age: {user.age}&lt;/p&gt;
  &lt;/div&gt;
);
const root = createRoot(document.getElementById(&quot;root&quot;));
root.render(element);
</code></pre>


A heading that updates with the counter value every second.

A single heading displaying `Counter: 0`.

A heading that displays the counter value but never updates.

What is the output of the following code?
```react
let counter = 0;
const root = createRoot(document.getElementById("root"));
setInterval(() => {
  const element = <h1>Counter: {counter++}</h1>;
  root.render(element);
}, 1000);
```

<p>What is the output of the following code?</p>
<pre><code class="language-react">let counter = 0;
const root = createRoot(document.getElementById(&quot;root&quot;));
setInterval(() =&gt; {
  const element = &lt;h1&gt;Counter: {counter++}&lt;/h1&gt;;
  root.render(element);
}, 1000);
</code></pre>


Test your understanding of React's fundamental concepts with this comprehensive quiz.

Before We Begin

JavaScript for React—A Quick Refresher

Introduction to React

React Components

Hooks: Managing States and Effects in React Components

React Router and Navigations

Conclusion

Quiz: Introduction to React