code: public static function toHtml5($strString)
  	{
  		$arrPregReplace = array
  		(
  			'/<(br|hr|img)([^>]*) \/>/i'                  => '<$1$2>',             // Close stand-alone tags
  			'/ (cellpadding|cellspacing|border)="[^"]*"/' => '',                   // Remove deprecated attributes
  			'/ rel="lightbox(\[([^\]]+)\])?"/'            => ' data-lightbox="$2"' // see #4073
  		);
  
  		$arrStrReplace = array
  		(
  			'<u>'                                              => '<span style="text-decoration:underline">',
  			'</u>'                                             => '</span>',
  			' target="_self"'                                  => '',
  			' onclick="window.open(this.href); return false"'  => ' target="_blank"',
  			' onclick="window.open(this.href);return false"'   => ' target="_blank"',
  			' onclick="window.open(this.href); return false;"' => ' target="_blank"'
  		);
  
  		$strString = preg_replace(array_keys($arrPregReplace), $arrPregReplace, $strString);
  		$strString = str_ireplace(array_keys($arrStrReplace), $arrStrReplace, $strString);
  
  		return $strString;
  	}
docs: Convert a string to HTML5
  
  @param string $strString The XHTML string
  
  @return string The HTML5 string