jsx
 
 
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import React from 'react';

const Hello = ({language}) => {
  let greeting;
  if (language === 'french') {
    greeting = 'Bonjour';
  } else if (language === 'spanish') {
    greeting = 'Hola';
  } else {
    greeting = 'Hello';
  }
  return (
    <h2>{greeting}</h2>
  );
}

export default Hello;

To use the Hello component, import it in another file and pass the language property:

jsx
 
 
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import React from 'react';
import Hello from './Hello';

const App = () => {
  return (
    <>
      <Hello language="english" />
      <Hello language="french" />
      <Hello language="spanish" />
    </>
  );
}

export default App;

React is a JavaScript library for building user interfaces. It allows developers to create reusable UI components and manage the state of the application efficiently. React uses a virtual DOM, which improves the performance of rendering and updating elements on the page. You can learn more about React here: https://reactjs.org/

In React, it is generally better to have several components instead of one large component. This is because breaking down a large component into smaller components can make the code more modular, easier to maintain, and easier to reuse. Additionally, smaller components can make it easier to reason about what is happening in the code, leading to better debugging and fewer errors.

Here is an example of how a React application can be structured using multiple components:

jsx
 
 
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// Parent component
function App() {
  return (
    <div className="App">
      <Header />
      <MainContent />
      <Footer />
    </div>
  );
}

// Child components
function Header() {
  return (
    <header>
      <h1>Welcome to my website!</h1>
      <nav>
        <ul>
          <li><a href="#">Home</a></li>
          <li><a href="#">About</a></li>
          <li><a href="#">Contact</a></li>
        </ul>
      </nav>
    </header>
  );
}

function MainContent() {
  return (
    <main>
      <p>This is the main content of my website.</p>
      <p>It is split into several smaller components.</p>
    </main>
  );
}

function Footer() {
  return (
    <footer>
      <p>Copyright © 2021</p>
    </footer>
  );
}

In this example, there are three smaller components (Header, MainContent, and Footer) that are combined to make up the larger App component.

React Query is a powerful library for managing server state and caching data. It makes fetching, caching, and updating asynchronous data in React applications a lot easier, and can simplify your code compared to managing state yourself. It is written in JavaScript and you can find the documentation and examples on their official website at https://react-query.tanstack.com/docs.

Here's an example of how you can use React Query to fetch data from an API:

jsx
 
 
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import { useQuery } from 'react-query';

function App() {
  const { data, isLoading, error } = useQuery('todos', () =>
    fetch('https://jsonplaceholder.typicode.com/todos').then(res =>
      res.json()
    )
  );

  if (isLoading) {
    return <div>Loading...</div>;
  }

  if (error) {
    return <div>Oops, something went wrong...</div>;
  }

  return (
    <ul>
      {data.map(item => (
        <li key={item.id}>{item.title}</li>
      ))}
    </ul>
  );
}

history.goBack() is a function in React Router that allows the user to navigate to the previous page in the browser history. If you want to define the state when using history.goBack(), you can pass the state object as a second argument to the history.push() method when navigating to the current page.

Here's an example code block in JavaScript:

javascript
 
 
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// defining state when navigating to current page
history.push('/current', { name: 'John' });

// go back to previous page
history.goBack();

In the above example, the current page is navigated to with the state object { name: 'John' }. When the history.goBack() method is called, the user will be taken to the previous page with the state from the '/current' page.

To prevent an input field from submitting until a user clicks the submit button in a React component, you can use the event.preventDefault() method that is called in the onSubmit handler for the form. Here's an example of how this can be done:

jsx
 
 
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import { useState } from 'react';

function MyForm() {
  const [inputValue, setInputValue] = useState('');

  function handleSubmit(event) {
    event.preventDefault(); // prevent the form from submitting
    console.log('Input value on submit: ', inputValue);
  }

  return (
    <form onSubmit={handleSubmit}>
      <label>
        Type something:
        <input
          type="text"
          value={inputValue}
          onChange={(event) => setInputValue(event.target.value)}
        />
      </label>
      <button type="submit">Submit</button>
    </form>
  );
}

In this example, the handleSubmit function is called when the form is submitted. The event.preventDefault() line prevents the form from actually submitting, giving you a chance to validate or process the input before submitting it to the server or updating the state of your React component. When the user clicks the "Submit" button, the input value is logged to the console.

To achieve this, we can use state property in React to show/hide the search query result. Here's an example in React JS:

jsx
 
 
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import React, { useState } from 'react';

function Search() {
  const [query, setQuery] = useState('');
  const [isResultShown, setIsResultShown] = useState(false);

  const handleSearch = () => {
    // perform query search here
    // set the search result as 'query'
    setIsResultShown(true);
  }

  return (
    <div>
      <input type="text" value={query} onChange={(e) => setQuery(e.target.value)} />
      <button onClick={handleSearch}>Search</button>
      {isResultShown && <h2>{query}</h2>}
    </div>
  );
}

In this example, we have two state variables - query to hold the search query and isResultShown to determine whether to show the search result or not. When the user clicks on the search button, handleSearch() function is called where we can perform the search query and set it to the query state. Finally, isResultShown is toggled to true, showing the h2 tag with the search result.

In React, a form is basically a collection of input controls that enables users to submit data to the application. The user's inputs can be processed automatically or sent to a server for processing.

To create a form in React, you can use the built-in form tag and add input fields using the input tag. Each input should have a name attribute that matches the state key you want to update when the user types in a value.

Here's an example of creating a basic form in React:

jsx
 
 
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import React, { useState } from 'react';

function Form() {
  const [formData, setFormData] = useState({});

  function handleChange(e) {
    setFormData({ ...formData, [e.target.name]: e.target.value });
  }

  function handleSubmit(e) {
    e.preventDefault();
    // Process the form data
    console.log(formData);
  }

  return (
    <form onSubmit={handleSubmit}>
      <label>
        Name:
        <input type="text" name="name" onChange={handleChange} />
      </label>
      <label>
        Email:
        <input type="email" name="email" onChange={handleChange} />
      </label>
      <button type="submit">Submit</button>
    </form>
  );
}

This example creates a form with two input fields for name and email. The handleChange function updates the formData state object whenever the user types in one of the fields. The handleSubmit function logs the entire form data to the console when the user submits the form.

In React, state is an object that stores information about the component's current state or state changes. The state object is accessible only within the component itself, and can be updated using the setState() method. When the state of a component changes, React will rerender the component and any child components that depend the updated state.

Here is an example of how state can be defined and used in a React component:

jsx
 
 
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import React, { useState } from 'react';

function Counter() {
  const [count, setCount] = useState(0);

  function increment() {
    setCount(count + 1);
  }

  return (
    <div>
      <p>Count: {count}</p>
      <button onClick={increment}>Increment</button>
    </div>
  );
}

In this example, count is the state variable, which is initialized with a value of 0 using the useState() hook. The increment() function updates the state by calling setCount(), passing in the new count value. Finally, the component renders the count value within a paragraph element and a button that, when clicked, calls the increment() function to update the state.

HTML:

html
 
 
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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Noodle Company Landing Page</title>
  <link rel="stylesheet" href="style.css">
</head>
<body>
  <header>
    <img src="logo.png" alt="Noodle Company Logo">
    <nav>
      <ul>
        <li><a href="#">Home</a></li>
        <li><a href="#">About Us</a></li>
        <li><a href="#">Product</a></li>
        <li><a href="#">Contact Us</a></li>
      </ul>
    </nav>
  </header>
  <main>
    <section id="about-us">
      <h2>About Us</h2>
      <div class="slideshow">
        <img src="slide1.png" alt="Slide 1">
        <img src="slide2.png" alt="Slide 2">
        <img src="slide3.png" alt="Slide 3">
      </div>
      <p>Insert summary of the company here.</p>
    </section>
    <section id="product">
      <h2>Product</h2>
      <div class="product-grid">
        <div class="product">
          <img src="product1.png" alt="Product 1">
          <div class="product-text">
            <h3>Product 1</h3>
            <p>Description of product 1.</p>
          </div>
        </div>
        <div class="product">
          <img src="product2.png" alt="Product 2">
          <div class="product-text">
            <h3>Product 2</h3>
            <p>Description of product 2.</p>
          </div>
        </div>
        <div class="product">
          <img src="product3.png" alt="Product 3">
          <div class="product-text">
            <h3>Product 3</h3>
            <p>Description of product 3.</p>
          </div>
        </div>
        <div class="product">
          <img src="product4.png" alt="Product 4">
          <div class="product-text">
            <h3>Product 4</h3>
            <p>Description of product 4.</p>
          </div>
        </div>
      </div>
    </section>
    <section id="contact-us">
      <h2>Contact Us</h2>
      <div class="contact-info">
        <p>Address: 123 Main St.</p>
        <p>Phone Number: (123) 456-7890</p>
        <p>Email: info@noodlecompany.com</p>
      </div>
      <div class="logo-slideshow">
        <img src="logo1.png" alt="Company Logo 1">
        <img src="logo2.png" alt="Company Logo 2">
        <img src="logo3.png" alt="Company Logo 3">
      </div>
    </section>
  </main>
</body>
</html>

CSS:

css
 
 
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/* Reset CSS */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* General Styles */
body {
  font-family: Arial, sans-serif;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
  background-color: #f2f2f2;
}

nav ul {
  display: flex;
  list-style: none;
}

nav li {
  margin: 0 0.5rem;
}

nav a {
  text-decoration: none;
  color: black;
  font-weight: bold;
}

main {
  padding: 2rem;
}

h2 {
  margin-bottom: 1rem;
}

/* About Us Styles */
.slideshow {
  display: flex;
  overflow: hidden;
}

.slideshow img {
  width: 100%;
  height: auto;
  object-fit: cover;
  animation: slide 10s infinite;
}

@keyframes slide {
  0% {
    opacity: 1;
    transform: scale(1);
  }
  25% {
    opacity: 0;
    transform: scale(1.1);
  }
  50% {
    opacity: 0;
    transform: scale(1.1);
  }
  75% {
    opacity: 0;
    transform: scale(1);
  }
  100% {
    opacity: 1;
    transform: scale(1);
  }
}

/* Product Styles */
.product-grid {
  display: grid;

html
 
 
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<!-- HTML code -->
<div class="progress-container">
  <div class="progress-bar" style="width: 50%"></div>
  <div class="progress-value">50</div>
</div>
<button id="minus-button">-</button>
<button id="plus-button">+</button>

css
 
 
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/* CSS code */
.progress-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin: 20px;
}
.progress-bar {
  width: 0%;
  height: 20px;
  margin-bottom: 10px;
  background-color: blue;
}
.progress-value {
  font-size: 18px;
}
button {
  font-size: 18px;
  padding: 10px;
  margin: 5px;
  border: none;
  border-radius: 5px;
  background-color: lightgray;
}
button:disabled {
  background-color: gray;
}

javascript
 
 
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// JavaScript code using React hooks
import React, { useState, useEffect } from 'react';

const ProgressBar = ({ value }) => {
  const [progress, setProgress] = useState(0);

  useEffect(() => {
    setProgress(value > 100 ? 100 : value < 0 ? 0 : value);
  }, [value]);

  const handleMinusClick = () => {
    setProgress(prevProgress => {
      const newProgress = prevProgress - 1;
      return newProgress < 0 ? 0 : newProgress;
    });
  };

  const handlePlusClick = () => {
    setProgress(prevProgress => {
      const newProgress = prevProgress + 1;
      return newProgress > 100 ? 100 : newProgress;
    });
  };

  return (
    <div className="progress-container">
      <div className="progress-bar" style={{ width: `${progress}%` }} />
      <div className="progress-value">{progress}</div>
      <button
        id="minus-button"
        onClick={handleMinusClick}
        disabled={progress <= 0}
      >
        -
      </button>
      <button
        id="plus-button"
        onClick={handlePlusClick}
        disabled={progress >= 100}
      >
        +
      </button>
    </div>
  );
};

export default ProgressBar;

To convert HTML code to React, you need to break down the HTML code into smaller React components.

Here are the basic steps:

1. Identify the repetitive or reusable parts of the HTML code and create a React component for them. This will help you to manage the code better by having smaller chunks that can be easily maintained.

2. Convert the remaining HTML into JSX. JSX is similar to HTML, but it allows you to write JavaScript code within it.

3. Replace the HTML tags with the equivalent JSX tags. For example, replace the class attribute with the className attribute and the for attribute with the htmlFor attribute.

4. Add the appropriate React syntax, such as props, state, and lifecycle methods to create a working React component.

Here's an example of how you could convert an HTML component to React:

HTML Code:

code
 
 
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<div class="container">
  <h1>Hello World!</h1>
  <p>This is a sample paragraph.</p>
</div>

React Code:

code
 
 
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import React from 'react';

function Container() {
  return (
    <div className="container">
      <h1>Hello World!</h1>
      <p>This is a sample paragraph.</p>
    </div>
  );
}

export default Container;

You can find more information about converting HTML to React in this article: Converting HTML to React.

To install axios, you can use either npm or yarn. Here's how to install axios with npm.

bash
 
 
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npm install axios

And with yarn.

bash
 
 
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yarn add axios

Here's a link to the npm package for axios: axios

Make sure you have Node.js installed before running these commands.

useEffect is a React Hook that lets you synchronize a component with the browser’s lifecycle events, so you can modify the component’s behavior or appearance as needed. You should use useEffect to perform actions that must be done synchronously with lifecycle changes, like setting up event listeners, fetching data or performing cleanups. You can learn more about useEffect on React's official documentation here: https://reactjs.org/docs/hooks-effect.html

Here's an example of using useEffect in JavaScript:

code
 
 
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import React, { useState, useEffect } from 'react';

function App() {
  const [data, setData] = useState(null);

  useEffect(() => {
    // Fetch data from an API when the component mounts
    fetch('https://api.example.com/data')
      .then(response => response.json())
      .then(data => setData(data));

    // Remove the event listener and clean up when the component unmounts
    return () => {
      document.removeEventListener('click', handleClick);
    }
  }, []);

  // Log the data to the console when it updates
  useEffect(() => {
    console.log(data);
  }, [data]);

  // Handle clicks on the document
  function handleClick() {
    console.log('Document clicked!');
  }

  return (
    <div>
      <h1>{data ? data.title : 'Loading...'}</h1>
    </div>
  );
}

export default App;

In this example, useEffect is used to fetch data from an API when the component mounts, log the data to the console when it updates, and remove an event listener and clean up when the component unmounts. The empty array [] as the second argument to useEffect indicates that we want to run the effect only once, when the component mounts, and not after every re-render. The data variable is included as a dependency array to the second useEffect so that it only logs the data when it updates.

React is a JavaScript library for building user interfaces. It allows developers to create reusable UI components and manage the state of an application. React was developed by Facebook and is maintained by a community of developers. It is often used to build single-page web applications and mobile applications. React uses a virtual DOM, which allows for efficient updates to the UI without having to reload the entire page. You can learn more about React at the official documentation: https://reactjs.org/

JSX (JavaScript XML) is an extension of JavaScript syntax used by ReactJS which allows us to write HTML syntax within the JavaScript code. It provides a way to structure and represent data in React components.

javascript
 
 
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const element = <h1>Hello, world!</h1>;

To get the current date in React, you can use the Date() function.

javascript
 
 
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const today = new Date();

This will create a Date object that contains the current date. Then you can format it however you'd like:

javascript
 
 
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const month = today.getMonth()+1;
const year = today.getFullYear();
const date = today. getDate();
const currentDate = month + "/" + date + "/" + year;

The older syntax for the code mentioned would be:

js
 
 
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onChange={function(e){ setValue(e.target.value) }}

In React, you can use the .map() method to iterate through an array and render a list of elements. The .map() method will take a callback as an argument and return a new array with the returned value of the callback.

Example in JavaScript:

javascript
 
 
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const arrayData = [1, 2, 3, 4, 5];

const mappedData = arrayData.map(item => item * 2);

In this example, the mappedData array will be equal to [2, 4, 6, 8, 10].

You can also use .map() to render a list of components, such as in this example:

javascript
 
 
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import React from "react";

const App = () => {
  const arrayData = [1, 2, 3, 4, 5];

  return (
    <ul>
      {arrayData.map(item => (
        <li key={item}>{item}</li>
      ))}
    </ul>
  );
};

This will return a list of elements with the values of data in the arrayData array. For more information on .map() in React, visit this page.

React Hooks are functions that let you ‘hook into’ React features from function components. They are mainly used for state management inside components. Using hooks, you can use local state inside simple components, write custom hooks to reuse your stateful logic and also use React’s built-in hooks like useState and useEffect which allow you to set local state and access lifecycle features from functional components.

For example you can use the useState hook to create a local state variable and set its initial value like this:

js
 
 
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import React, { useState } from "react";

const Example = () => {
  const [count, setCount] = useState(0);

  return (
    <div>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>
        Click me
      </button>
    </div>
  );
}

React also has two other built-in hooks, useEffect and useContext, as well as many transition and form hooks.

For more information, please see the official React documentation: https://reactjs.org/docs/hooks-intro.html

The createContext React hook is used to create a Context object that can then be used to pass data through the Component tree. The provider prop is used to provide the context data which should be available to any components below it in the tree.

For example, using the following code we can create a context and provide an initial value for it:

javascript
 
 
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const { Provider, Consumer } = React.createContext(initialValue);

The Provider is an object that can be used to wrap child components, providing the initial value to be passed through the Context object. The Consumer object will be used by the child components to access the values provided by the Provider.

For example, using the following code, we can wrap a child component with the Provider and access the values provided in it:

javascript
 
 
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const App = () => (
  <Provider value={myValue}>
    <MyChildComponent />
  </Provider>
);

const MyChildComponent = () => (
  <Consumer>
    {value => {
      // Do something with the value
    }}
  </Consumer>
);

This error usually means that npm is not able to find the specified file. Check the pathname and make sure that it is in the correct location. You can also try running npm cache clean --force to clear the npm cache. For more information, see this npm page.

jsx
 
 
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import React, { useState } from 'react'
import styled from 'styled-components'

const DropdownContainer = styled.div`
  display: inline-block;
  position: relative;
`

const DropdownMenu = styled.div`
  background-color: #f9f9f9;
  display: none;
  padding: 12px 16px;
  position: absolute;
  right: 0;
  z-index: 1;
`

const DropdownButton = styled.button`
  background-color: transparent;
  border: none;
  color: inherit;

  &:hover + & {
    display: inline-block;
  }
`

function App() {
  const [menuVisible, setMenuVisible] = useState(false)

  const toggleMenu = () => {
    setMenuVisible(!menuVisible)
  }

  return (
    <DropdownContainer>
     <DropdownButton onClick={toggleMenu}>Dropdown</DropdownButton> 
      {menuVisible && (
        <DropdownMenu>
          <ul>
            <li>Option 1</li>
            <li>Option 2</li>
            <li>Option 3</li>
            <li>Option 4</li>
          </ul>
        </DropdownMenu>
      )}
    </DropdownContainer>
  )
}

jsx
 
 
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const CityTemperature = () => {
  const city = "San Francisco"; 
  const temperature = "70°F"; 

  return (
    <p>The temperature in {city} is {temperature}.</p>
  )
}; 

HTML:

html
 
 
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<form>
  <label>
    City:
    <input type="text" id="city" name="city">
  </label>
  <br>
  <button type="submit" onclick="getTemperature()">Check Temperature</button>
</form>
<p id="temperature"></p>

CSS:

css
 
 
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form {
    width: 250px;
    margin: 0 auto
}

JavaScript:

javascript
 
 
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function getWeather(city) {
  fetch(`http://api.openweathermap.org/data/2.5/weather?q=${city}&appid=***********`)
    .then((response) => response.json())
    .then((data) => {
      let temp = data.main.temp;
      document.getElementById("temperature").innerHTML = `The temperature of ${city} is ${temp} K.`;
    });
}

function getTemperature() {
  let city = document.getElementById("city").value;
  getWeather(city);
  document.getElementById("city").value = "";
}