src/index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Caesar Cipher</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
    <div class="container">
        <div id="heading-container">
            <h1>CAESAR CIPHER</h1>
        </div>

        <div id="main-container">
            <!-- Controls section -->
            <!-- This section contains the controls for encoding/decoding and setting the shift key -->
            <div class="box">
                <div class="heading">
                    <h2>Controls</h2>
                </div>

                <form id="controls">
                    <!-- Encode/Decode radio buttons -->
                    <!-- User can select whether to encode or decode the message -->
                    <div class="row">
                        <div>
                            <input type="radio" id="encode" name="code" value="encode" checked>
                            <label for="encode">Encode</label>
                        </div>

                        <div>
                            <input type="radio" id="decode" name="code" value="decode">
                            <label for="decode">Decode</label>
                        </div>
                    </div>

                    <!-- Shift key input -->
                    <!-- User can enter the shift key value for the Caesar cipher -->
                    <div class="row">
                        <div>
                            <label for="shift-input">Shift Key:</label>
                            <input type="number" id="shift-input" name="shift" value="3" min="1" max="25">
                        </div>
                    </div>

                    <!-- Apply button -->
                    <!-- Clicking this button triggers the encoding/decoding process -->
                    <div>
                        <button type="submit">Apply</button>
                    </div>
                </form>
            </div>

            <!-- Input section -->
            <!-- This section displays the input text area for the user to enter the message -->
            <div class="box">
                <div class="heading">
                    <h2 id="heading-input">Plaintext</h2>
                </div>
                <textarea id="input-text" rows="6"></textarea>
            </div>

            <!-- Output section -->
            <!-- This section displays the output text area with the encoded/decoded message -->
            <div class="box">
                <div class="heading">
                    <h2 id="heading-output">Ciphertext</h2>
                </div>
                <div class="output-container">
                    <textarea id="output-text" rows="6" readonly></textarea>
                    <button id="copy-btn">Copy</button>
                </div>
            </div>
        </div>

        <!-- Error message container -->
        <!-- This container displays any error messages to the user -->
        <div id="error-message"></div>
    </div>

    <script src="caesar.js"></script>
</body>
</html>