<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
</head>
<body>
<textarea id="textId">Some copying text</textarea>
<button id="copyBtn">Copy Button</button>
<script>
document.getElementById("copyBtn")
.onclick = function() {
let text = document.getElementById("textId").value;
navigator.clipboard.writeText(text)
.then(() => {
alert('Text copied to clipboard');
})
.catch(err => {
alert('Error in copying text: ', err);
});
}
</script>
</body>
</html>