$('#dialog_title_span').text("new dialog title");
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>text demo</title>
<style>
p {
color: blue;
margin: 8px;
}
</style>
<script src="https://code.jquery.com/jquery-3.5.0.js"></script>
</head>
<body>
<p>Test Paragraph.</p>
<script>
$( "p" ).text( "<b>Some</b> new text." );
</script>
</body>
</html>