core-bundle/src/Resources/contao/classes/Frontend.php
protected function prepareMetaDescription($strText)
	{
		$strText = $this->replaceInsertTags($strText, false);
		$strText = strip_tags($strText);
		$strText = str_replace("\n", ' ', $strText);
		$strText = StringUtil::substr($strText, 320);

		return trim($strText);
	}
protected function prepareMetaDescription($strText)
	{
		$strText = $this->replaceInsertTags($strText, false);
		$strText = strip_tags($strText);
		$strText = str_replace("\n", ' ', $strText);
		$strText = StringUtil::substr($strText, 320);

		return trim($strText);
	}
Prepare a text to be used in the meta description tag

@param string $strText

@return string