Register Button in Text Tab of WYSIWYG Editor in WordPress

<?php
	// Add more buttons to the html editor
	function add_quicktags() {
		if (wp_script_is('quicktags')) {
?>
		<script type="text/javascript">
		QTags.addButton(
			'example_input',
			'input',
			prompt
		);

		function prompt() {
			var value = prompt('Enter an input value:', '');

			if (value) {
				QTags.insertContent('<input type="text" value="' + value + '" />');
			}
		}
		</script>
<?php
		}
	}
	add_action('admin_print_footer_scripts', 'add_quicktags');
?>