Add strikethrough back

system/admin/editor/js/Markdown.Editor.js

@@ -1483,7 +1483,7 @@
             buttons.bold = makeButton("wmd-bold-button", getString("bold"), "fa fa-bold", bindCommand("doBold"));
             buttons.italic = makeButton("wmd-italic-button", getString("italic"), "fa fa-italic", bindCommand("doItalic"));
             buttons.heading = makeButton("wmd-heading-button", getString("heading"), "fa fa-header", bindCommand("doHeading"));
-            //buttons.strikethrough = makeButton("wmd-strikethrough-button", getString("strikethrough"), "fa fa-strikethrough", bindCommand("doStrikethrough"));
+            buttons.strikethrough = makeButton("wmd-strikethrough-button", getString("strikethrough"), "fa fa-strikethrough", bindCommand("doStrikethrough"));
             //makeSpacer(1);
             buttons.olist = makeButton("wmd-olist-button", getString("olist"), "fa fa-list-ol", bindCommand(function (chunk, postProcessing) {
                 this.doList(chunk, postProcessing, true);

system/vendor/michelf/php-markdown/Michelf/MarkdownExtra.php

@@ -139,6 +139,7 @@ class MarkdownExtra extends \Michelf\Markdown {
 		);
 		$this->span_gamut += array(
 			"doFootnotes"        => 5,
+			"doStrikethrough"    => 55,
 			"doAbbreviations"    => 70,
 		);
 
@@ -1890,4 +1891,32 @@ class MarkdownExtra extends \Michelf\Markdown {
 		}
 		return $matches[0];
 	}
+	
+	protected function doStrikethrough($text) {
+		#
+		# Strikethrough:
+		#    in:  text ~~deleted~~ from doc
+		#    out: text <del>deleted</del> from doc
+		#
+			$parts = preg_split('/(?<![~])(~~)(?![~])/', $text, null, PREG_SPLIT_DELIM_CAPTURE);
+			
+			//don't bother if nothing to do...
+			if(count($parts) <= 1)
+				return $text;
+			
+			$inTag = false;
+			foreach($parts as &$part) {
+				if($part == '~~') {
+					$part = ($inTag ? '</del>' : '<del>');
+					$inTag = !$inTag;
+				}
+			}
+			
+			//no hanging delimiter
+			if($inTag)
+				$parts[] = '</del>';
+			
+			return implode('', $parts);
+	}
+		
 }