cs1.diff

--- a/cs1.lua
+++ b/cs1.lua
@@ -25,7 +25,7 @@ delare variables here that have page-wide scope
 
 ]]
 
-local Preview_mode = false;														-- flag indicating that we are rendering a preview page (Show preview button)
+local is_preview_result = nil;														-- flag indicating that we are rendering a preview page (Show preview button)
 
 --[[--------------------------< F I R S T _ S E T >------------------------------------------------------------
 
@@ -38,6 +38,13 @@ the for-loop before it reached the actual end of the list.
 
 ]]
 
+local function is_preview_mode ()
+	if ( is_preview_result == nil ) then
+		is_preview_result = ( frame:preprocess( "{{REVISIONID}}" ) == "" )
+	end
+	return is_preview_result
+end
+
 local function first_set (list, count)
 	local i = 1;
 	while i <= count do															-- loop through all items in list
@@ -1795,7 +1802,7 @@ local function archive_url_check (url, date)
 
 	if url:match('//web%.archive%.org/save/') then								-- if a save command url, we don't want to allow saving of the target page 
 		table.insert( z.message_tail, { set_error( 'archive_url', {'save command'}, true ) } );	-- add error message
-		if Preview_mode then
+		if is_preview_mode() then
 			return url:gsub ('(//web%.archive%.org)/save/', '%1/*/', 1), date;	-- preview mode: modify and return ArchiveURL and ArchiveDate
 		else
 			return '', '';														-- return empty strings for archiveURL and ArchiveDate
@@ -1825,7 +1832,7 @@ local function archive_url_check (url, date)
 	end
 																				-- if here something not right so
 	table.insert( z.message_tail, { set_error( 'archive_url', {err_msg}, true ) } );	-- add error message and
-	if Preview_mode then
+	if is_preview_mode() then
 		return url, date;														-- preview mode so return archiveURL and ArchiveDate
 	else
 		return '', '';															-- return empty strings for archiveURL and ArchiveDate
@@ -3282,14 +3289,6 @@ function cs1.citation(frame)
 	get_coins_pages = metadata.get_coins_pages;
 	COinS = metadata.COinS;
 
-	
-	Preview_mode = frame:preprocess('{{REVISIONID}}');							-- use magic word to get revision id
-	if is_set (Preview_mode) then												-- if there is a value then this is not a preiview
-		Preview_mode = false;
-	else
-		Preview_mode = true;													-- no value (nil or empty string) so this is a preview
-	end
-	
 	local args = {};
 	local suggestions = {};
 	local error_text, error_state;