sanitize.php

<?php

if (!function_exists('remove_html_comments')){
	/**
	 * @param string $content (html)
	 * @return string
	 */
	function remove_html_comments($content = null)
	{
		$result = preg_replace('/<!--(.|\s)*?-->/', '', $content);
		return $result;
	}
}

if (!function_exists('sanitize_output')) {
	/**
	 * @param string $buffer (html)
	 * @return string
	 */
	function sanitize_output($buffer = null)
	{
		$search 	= ['/\>[^\S ]+/s', '/[^\S ]+\</s', '/(\s)+/s']; // Strip whitespaces after and before tags, except space and shorten multiple whitespace sequences
		$replace	= ['>', '<', '\\1'];

		$result = preg_replace($search, $replace, $buffer);
		$result = remove_html_comments($result); // Remove HTML Comments

		return $result;
	}
}
ob_start("sanitize_output");