JavaScript onselect events

The onselect event occurs when some text has been selected in an HTML element.

EXAMPLE

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>onselect example</title>
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
    
    <style>
        .container {
            max-width: 400px;
            margin: 30px auto;
            padding: 20px;
            font-family: Arial, sans-serif;
        }

        textarea {
            width: 100%;
            padding: 10px;
            margin: 10px 0;
            border: 2px solid #ddd;
            border-radius: 4px;
        }

        #message {
            margin-top: 15px;
            padding: 10px;
            background-color: #e3f2fd;
            color: black;
            border-radius: 4px;
            display: none;
        }
    </style>
</head>
<body>
    <div class="container">
        <h3>Select some text:</h3>
        
        <textarea onselect="textSelected()" rows="4">This is test text. Try selecting part of this text to see how the 
        onselect event works.</textarea>
        
        <div id="message"></div>
    </div>

    <script>
        function textSelected() {
            let message = document.getElementById("message");
            message.style.display = "block";
            message.innerHTML = "Great! You selected some text!";
        }
    </script>
</body>
</html>

RESULT