Strips Markdown from Text - PHP port of https://github.com/stiang/remove-markdown

strip_markdown.php

<?php

function strip_markdown( $md = '', $options = [] ) {

	// char to insert instead of stripped list leaders (default: '')
	$options['listUnicodeChar'] = isset( $options['listUnicodeChar'] ) ? $options['listUnicodeChar'] : false;
	// strip list leaders (default: true)
	$options['stripListLeaders'] = isset( $options['stripListLeaders'] ) ? $options['stripListLeaders'] : true;
	// support GitHub-Flavored Markdown (default: true)
	$options['gfm'] = isset( $options['gfm'] ) ? $options['gfm'] : true;
	// replace images with alt-text, if present (default: true)
	$options['useImgAltText'] = isset( $options['useImgAltText'] ) ? $options['useImgAltText'] : true;

	$output = $md;
	$output = preg_replace( '/^(-\s*?|\*\s*?|_\s*?){3,}\s*$/m', '', $output );

	try {
		if( $options['stripListLeaders'] ) {
			if( $options['listUnicodeChar'] ) {
				$output = preg_replace( '/^([\s\t]*)([\*\-\+]|\d+\.)\s+/m', $options['listUnicodeChar'].' $1', $output );
			}
			else {
				$output = preg_replace( '/^([\s\t]*)([\*\-\+]|\d+\.)\s+/m', '$1', $output );
			}
		}
		if( $options['gfm'] ) {
			// Header
			$output = preg_replace( '/\n={2,}/', '\n', $output );
			// Fenced codeblocks
			$output = preg_replace( '/~{3}.*\n/', '', $output );
			// Strikethrough
			$output = preg_replace( '/~~/', '', $output );
			// Fenced codeblocks
			$output = preg_replace( '/`{3}.*\n/', '', $output );
		}
		// Remove HTML tags
		$output = preg_replace( '/<[^>]*>/', '', $output );
		// Remove setext-style headers
		$output = preg_replace( '/^[=\-]{2,}\s*$/', '', $output );
		// Remove footnotes?
		$output = preg_replace( '/\[\^.+?\](\: .*?$)?/', '', $output );
		$output = preg_replace( '/\s{0,2}\[.*?\]: .*?$/', '', $output );
		// Remove images
		$output = preg_replace( '/\!\[(.*?)\][\[\(].*?[\]\)]/', ( $options['useImgAltText'] ? '$1' : '' ), $output );
		// Remove inline links
		$output = preg_replace( '/\[(.*?)\][\[\(].*?[\]\)]/', '$1', $output );
		// Remove blockquotes
		$output = preg_replace( '/^\s{0,3}>\s?/', '', $output );
		// Remove reference-style links?
		$output = preg_replace( '/^\s{1,2}\[(.*?)\]: (\S+)( ".*?")?\s*$/', '', $output );
		// Remove atx-style headers
		$output = preg_replace( '/^(\n)?\s{0,}#{1,6}\s+| {0,}(\n)?\s{0,}#{0,} {0,}(\n)?\s{0,}$/m', '$1$2$3', $output );
		// Remove emphasis (repeat the line to remove double emphasis)
		$output = preg_replace( '/([\*_]{1,3})(\S.*?\S{0,1})\1/', '$2', $output );
		$output = preg_replace( '/([\*_]{1,3})(\S.*?\S{0,1})\1/', '$2', $output );
		// Remove code blocks
		$output = preg_replace( '/(`{3,})(.*?)\1/m', '$2', $output );
		// Remove inline code
		$output = preg_replace( '/`(.+?)`/', '$1', $output );
		// Replace two or more newlines with exactly two? Not entirely sure this belongs here...
		$output = preg_replace( '/\n{2,}/', '\n\n', $output );

	}
	catch( Exception $e ) {
		return $md;
	}

	return $output;
}

feel free to clone and use - give credit to https://github.com/stiang