React js check if input file is empty

<!DOCTYPE html>
<html>
  <head>
    <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 } = React;
      const App = () => {
        const [file, setFile] = useState(null);

const handleFileChange = (event) => {
          const selectedFile = event.target.files[0];

if (selectedFile) {
            const reader = new FileReader();
            reader.onload = () => {
              const fileContent = reader.result;

if (fileContent.length > 0) {
                // File is not empty
                setFile(selectedFile);
              } else {
                // File is empty
                setFile(null);
              }
            };

reader.readAsText(selectedFile);
          } else {
            // No file selected
            setFile(null);
          }
        };

const handleSubmit = (event) => {
          event.preventDefault();
          // Perform the form submission or further processing here
        };

return (
          <div className="container">
            <h3>React js check if input file is empty </h3>
            <input type="file" onChange={handleFileChange} />
            <button type="submit" onClick={handleSubmit} disabled={!file}>
              Submit
            </button>
          </div>
        );
      };

ReactDOM.render(<App />, document.getElementById("app"));
    </script>
    <style>
      .container {
        display: flex;
        flex-direction: column;
        align-items: center;
        padding: 20px;
        box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.12),
          0 2px 4px 0 rgba(0, 0, 0, 0.24);
        width: 400px;
        margin: 0 auto;
      }

input[type="file"] {
        margin-bottom: 10px;
      }

button[type="submit"] {
        padding: 10px 20px;
        background-color: #3498db;
        color: #fff;
        border: none;
        border-radius: 4px;
        font-size: 16px;
        cursor: pointer;
        transition: background-color 0.3s ease;
      }

button[type="submit"]:disabled {
        background-color: #ccc;
        cursor: not-allowed;
      }

button[type="submit"]:hover {
        background-color: #2980b9;
      }
    </style>
  </body>
</html>