React Js Check First Letter of String is Uppercase

<!DOCTYPE html>
<html>

<body>
  <div id="app"></div>
  <script type="text/babel">
    const { useState } = React;
    function App() {
      const [input, setInput] = useState('Font aweosme icons');
      const isFirstLetterUppercase = input.length > 0 && input[0] === input[0].toUpperCase();

);
    }
    ReactDOM.render(<App />, document.getElementById("app"));
  </script>

.input-field {
      padding: 10px;
      border: 2px solid #007BFF;
      /* Blue border */
      border-radius: 5px;
      margin-bottom: 10px;
      font-size: 16px;
      width: 300px;
      outline: none;
    }

.check-button {
      background-color: #007BFF;
      /* Blue background */
      color: white;
      border: none;
      border-radius: 5px;
      padding: 10px 20px;
      cursor: pointer;
      font-size: 16px;
      transition: background-color 0.3s;
    }

.check-button:hover {
      background-color: #0056b3;
      /* Darker blue on hover */
    }
  </style>
</body>

</html>

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<!DOCTYPE html>
<html>
​
<head>
  <meta charset="UTF-8" />
  <script src="https://unpkg.com/react@17.0.2/umd/react.development.js"></script>
  <script src="https://unpkg.com/react-dom@17.0.2/umd/react-dom.development.js"></script>
  <script src="https://unpkg.com/@babel/standalone@7.14.7/babel.min.js"></script>
</head>
​
<body>
  <div id="app"></div>
  <script type="text/babel">
    const { useState } = React;
    function App() {
      const [input, setInput] = useState('Font aweosme icons');
      const isFirstLetterUppercase = input.length > 0 && input[0] === input[0].toUpperCase();
​
      const showAlert = () => {
        const message = isFirstLetterUppercase
          ? 'The first letter is uppercase.'
          : 'The first letter is not uppercase.';
        alert(message);
      };
      return (
        <div className='container'>
          <h3>React Js Check First Letter Of String Is Uppercase </h3>
          <input
            className='input-field'
            type="text"
            value={input}
            onChange={(e) => setInput(e.target.value)}
            placeholder="Enter a string"
          />
          <button className='check-button' onClick={showAlert}>Check Uppercase</button>
        </div>
​
      );
    }
    ReactDOM.render(<App />, document.getElementById("app"));
  </script>
​
​
  <style>
    .container {
      font-family: Arial, sans-serif;
      padding: 20px;
      border-radius: 5px;
      box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.2);
      max-width: 600px;
      margin: 0 auto;
      text-align: center;
    }
​
    .input-field {
      padding: 10px;
      border: 2px solid #007BFF;
      /* Blue border */
      border-radius: 5px;
      margin-bottom: 10px;
      font-size: 16px;
      width: 300px;
      outline: none;
    }
​
    .check-button {
      background-color: #007BFF;
      /* Blue background */
      color: white;
      border: none;
      border-radius: 5px;
      padding: 10px 20px;
      cursor: pointer;
      font-size: 16px;
      transition: background-color 0.3s;
    }
​
    .check-button:hover {
      background-color: #0056b3;
      /* Darker blue on hover */
    }
  </style>
</body>
​
</html>