onclick_changetext_js.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #demo{
            width: 200px;
            height: 20px;
            padding: 5px;
        }
        button{
            margin: 5px;
            padding: 5px;
        }
    </style>
</head>
<body>
    <h1>Javascript example</h1>
    <h3>Onclick change text</h3>
    <p id="demo">Hello there</p>
    <button type="button" onclick="document.getElementById('demo').innerHTML='You can always do this!'">Show more</button><br>
    <button type="button" onclick="document.getElementById('demo').innerHTML='Hello there'">Show less</button>
</body>
</html>