React Js Counter App

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.development.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.2/umd/react-dom.development.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.26.0/babel.min.js"></script>
</head>
<body>
  <div id="app"></div>
  <script type="text/babel">
    const { useState, useEffect } = React;
    function App() {
      const [count, setCount] = useState(0);
      const [isRunning, setIsRunning] = useState(false);

useEffect(() => {
        let interval;

if (isRunning) {
          interval = setInterval(() => {
            setCount((prevCount) => prevCount + 1);
          }, 1000); // Update the count every second (1000 ms).
        } else {
          clearInterval(interval);
        }

return () => clearInterval(interval);
      }, [isRunning]);

const startCounter = () => {
        setIsRunning(true);
      };

const stopCounter = () => {
        setIsRunning(false);
      };

const resetCounter = () => {
        setCount(0);
        setIsRunning(true);
      };

return (
        <div className='container'>
          <h3>React Js Counter App</h3>
          <p className='count-text'>Count: {count}</p>
          <button className='start-button' disabled={isRunning} onClick={startCounter}>Start</button>
          <button className='stop-button' disabled={!isRunning} onClick={stopCounter}>Stop</button>
          <button className='reset-button' onClick={resetCounter}>Reset</button>
        </div>

);
    }
    ReactDOM.render(<App />, document.getElementById("app"));
  </script>
  <style>
    * {
      box-sizing: border-box;
    }

.container {
      margin: 0 auto;
      width: 600px;
      text-align: center;
      background: #fff;
      border-radius: 5px;
      padding: 20px;
      box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
    }

/* Count text styles */
    .count-text {
      font-size: 24px;
      color: #333;
      margin: 10px 0;
    }

/* Button styles */
    button {
      padding: 10px 20px;
      margin: 5px;
      border: none;
      border-radius: 5px;
      cursor: pointer;
      font-size: 16px;
      font-weight: bold;
    }

/* Start button styles */
    .start-button {
      background-color: #27ae60;
      color: #fff;
    }

.start-button:hover {
      background-color: #219049;
    }

/* Stop button styles */
    .stop-button {
      background-color: #e74c3c;
      color: #fff;
    }

.stop-button:hover {
      background-color: #d64131;
    }

/* Reset button styles */
    .reset-button {
      background-color: #3498db;
      color: #fff;
    }

.reset-button:hover {
      background-color: #2980b9;
    }

button:disabled {
      background-color: #ccc;
      cursor: not-allowed;
    }
  </style>
</body>

</html>

 
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.2/umd/react.development.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.2/umd/react-dom.development.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.26.0/babel.min.js"></script>
</head>
<body>
  <div id="app"></div>
  <script type="text/babel">
    const { useState, useEffect } = React;
    function App() {
      const [count, setCount] = useState(0);
      const [isRunning, setIsRunning] = useState(false);
​
      useEffect(() => {
        let interval;
​
        if (isRunning) {
          interval = setInterval(() => {
            setCount((prevCount) => prevCount + 1);
          }, 1000); // Update the count every second (1000 ms).
        } else {
          clearInterval(interval);
        }
​
        return () => clearInterval(interval);
      }, [isRunning]);
​
      const startCounter = () => {
        setIsRunning(true);
      };
​
      const stopCounter = () => {
        setIsRunning(false);
      };
​
      const resetCounter = () => {
        setCount(0);
        setIsRunning(true);
      };
​
      return (
        <div className='container'>
          <h3>React Js Counter App</h3>
          <p className='count-text'>Count: {count}</p>
          <button className='start-button' disabled={isRunning} onClick={startCounter}>Start</button>
          <button className='stop-button' disabled={!isRunning} onClick={stopCounter}>Stop</button>
          <button className='reset-button' onClick={resetCounter}>Reset</button>
        </div>
​
      );
    }
    ReactDOM.render(<App />, document.getElementById("app"));
  </script>
  <style>
    * {
      box-sizing: border-box;
    }
​
    .container {
      margin: 0 auto;
      width: 600px;
      text-align: center;
      background: #fff;
      border-radius: 5px;
      padding: 20px;
      box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
    }
​
    /* Count text styles */
    .count-text {
      font-size: 24px;
      color: #333;
      margin: 10px 0;
    }
​
    /* Button styles */
    button {
      padding: 10px 20px;
      margin: 5px;
      border: none;
      border-radius: 5px;
      cursor: pointer;
      font-size: 16px;
      font-weight: bold;
    }
​
    /* Start button styles */
    .start-button {
      background-color: #27ae60;
      color: #fff;
    }
​
    .start-button:hover {
      background-color: #219049;
    }
​
    /* Stop button styles */
    .stop-button {
      background-color: #e74c3c;
      color: #fff;
    }
​
    .stop-button:hover {
      background-color: #d64131;
    }
​
    /* Reset button styles */
    .reset-button {
      background-color: #3498db;
      color: #fff;
    }
​
    .reset-button:hover {
      background-color: #2980b9;
    }
​
    button:disabled {
      background-color: #ccc;
      cursor: not-allowed;
    }
  </style>
</body>
​
</html>