> For the complete documentation index, see [llms.txt](https://reactjs.koida.tech/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://reactjs.koida.tech/react-in-the-beginning/lesson-1-demo-build-a-simple-react-app-fast.md).

# Lesson 1 - Demo: Build a Simple React App - Fast

### Sign in to CodeSandbox

{% embed url="<https://codesandbox.io>" %}

Demo on codesandbox.io cloud web

API endpoint: <https://dog.ceo/api/breeds/image/random>

<figure><img src="/files/TA1DclKsN83V1mxk2s1m" alt=""><figcaption></figcaption></figure>

Step 1.  Sign in to CodeSandbox&#x20;

Step 2. In Dashboard,  click <mark style="color:red;">**+Create**</mark> button

* Chose React(TS) template
* Configure your project and use default setting&#x20;
* Click "Create Sandbox" button

Step 3. You are now in React Project editor  mode. You can find all files for React in left panel.:

```jsx
// App.jsx

import { useState } from "react";
import "./styles.css";

export default function App() {
  const [image, setImage] = useState("");
  async function getRandomDog() {
    const data = await fetch("https://dog.ceo/api/breeds/image/random");
    const res = await data.json();
    console.log("Result : ", res.message);
    setImage(res.message);
  }
  return (
    <div className="App">
      <h1>Hello Puppy</h1>
      <h3> Fetch puppy from remote site(API)! </h3>
      <button onClick={getRandomDog}> Get me a puppy </button>
      <div>
        <img src={image} alt="" />
      </div>
    </div>
  );
}
```

```jsx
// index.jsx

import React from "react";
import ReactDOM from "react-dom/client";
import App from "./App";

const rootElement = document.getElementById("root")!;
const root = ReactDOM.createRoot(rootElement);

root.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>
);
```

```css
// styles.css
.App {
  font-family: sans-serif;
  text-align: center;
}
button {
  background-color: bisque;
  color: brown;
  margin-bottom: 3px;
}
img {
  width: 70%;
}
```


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