React Js Check Element Already Exist in Array if not Add

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8" />
  <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;

function App() {
      const [arrayState, setArrayState] = useState(['Apple', 'Banana', 'Grapes']);
      const [inputValue, setInputValue] = useState('');

const addElementIfNotExists = () => {
        // Check if the inputValue is not empty
        if (inputValue.trim() !== '') {
          // Convert the inputValue and all elements in the array to lowercase
          const lowercaseInputValue = inputValue.toLowerCase();
          const lowercaseArray = arrayState.map(element => element.toLowerCase());

// Check if the lowercaseInputValue exists in the lowercaseArray
          if (lowercaseArray.includes(lowercaseInputValue)) {
            // If it already exists, show an alert
            alert(`Element "${inputValue}" already exists in the array.`);
          } else {
            // If it doesn't exist, add it to a new copy of the array
            const newArray = [...arrayState, inputValue];
            // Update the state with the new array
            setArrayState(newArray);
            // Clear the input field after adding the element
            setInputValue('');
          }
        }
      };

return (
        <div className='container'>
          <h1 className='title'>Check if an Element exists in an Array in React</h1>
          <ul className='list'>
            {arrayState.map((element, index) => (
              <li key={index} className='list-item'>{element}</li>
            ))}
          </ul>
          <input
            type="text"
            className='input-field'
            value={inputValue}
            onChange={(e) => setInputValue(e.target.value)}
            placeholder="Enter an element"
          />
          <button className='add-button' onClick={addElementIfNotExists}>Add Element</button>
        </div>

);
    }
    ReactDOM.render(<App />, document.getElementById("app"));
  </script>
  <style>
    .container {
      max-width: 600px;
      margin: 0 auto;
      padding: 20px;
      border-radius: 8px;
      box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    }

.title {
      font-size: 24px;
      font-weight: bold;
      margin-bottom: 20px;
    }

.list {
      list-style: none;
      padding: 0;
    }

.list-item {
      font-size: 18px;
      margin-bottom: 10px;
    }

.input-field {
      padding: 8px;
      font-size: 16px;
      border: 1px solid #ccc;
      border-radius: 4px;
      margin-bottom: 10px;
    }

.add-button {
      padding: 8px 16px;
      font-size: 16px;
      background-color: #007bff;
      color: #fff;
      border: none;
      border-radius: 4px;
      cursor: pointer;
    }

.add-button:hover {
      background-color: #0056b3;
    }
  </style>
</body>

</html>