Le code suivant permet, en Javascript, de sélectionner le contenu d'un champ en cliquant sur un bouton :
<html>
<head>
<script>
function displayResult() {
document.getElementById("myTextarea").select();
}
</script>
</head>
<body>
<textarea id="myTextarea" cols="20"> At W3Schools you will find all the Web-building tutorials you need, from basic HTML to advanced XML, SQL, ASP, and PHP. </textarea>
<br />
<button type="button" onclick="displayResult()">Select contents of text area</button>
</body>
</html>