fix(codeblock): match whitespace but not newlines (#4625)

.github/workflows/stale.yml

@@ -15,4 +15,4 @@ jobs:
           This issue has been automatically marked as stale because lack of
           recent activity. It will be closed if no further activity occurs. Thank you
           for your contributions.
-        exempt-issue-labels: bug,discussion,"help wanted",need-verify,need-investigation,pending-reply,proposal,feature-request,enhancement,documentation
+        exempt-issue-labels: bug,discussion,help wanted,need-verify,need-investigation,pending-reply,proposal,feature-request,enhancement,documentation

lib/plugins/filter/before_post_render/backtick_code_block.js

@@ -2,7 +2,7 @@
 
 let highlight, prismHighlight;
 
-const rBacktick = /^((?:[^\S\r\n]*>){0,3}[^\S\r\n]*)(`{3,}|~{3,})[^\S\r\n]*((?:.*?[^`\s])?)[^\S\r\n]*\n((?:[\s\S]*?\n)?)(?:(?:[^\S\r\n]*>){0,3}[^\S\r\n]*)\2\s?(\n+|$)/gm;
+const rBacktick = /^((?:[^\S\r\n]*>){0,3}[^\S\r\n]*)(`{3,}|~{3,})[^\S\r\n]*((?:.*?[^`\s])?)[^\S\r\n]*\n((?:[\s\S]*?\n)?)(?:(?:[^\S\r\n]*>){0,3}[^\S\r\n]*)\2[^\S\r\n]?(\n+|$)/gm;
 const rAllOptions = /([^\s]+)\s+(.+?)\s+(https?:\/\/\S+|\/\S+)\s*(.+)?/;
 const rLangCaption = /([^\s]+)\s*(.+)?/;
 

test/scripts/filters/backtick_code_block.js

@@ -463,6 +463,23 @@ describe('Backtick code block', () => {
       codeBlock(data);
       data.content.should.not.contain('`');
     });
+
+    // test for Issue #4573
+    it('ignore trailing spaces but not newlines', () => {
+      const data = {
+        content: [
+          '``` js',
+          code,
+          '```',
+          '',
+          '# New line'
+        ].join('\n')
+      };
+
+      codeBlock(data);
+      console.log(data.content);
+      data.content.should.contain('\n\n# New line');
+    });
   });
 
   describe('prismjs', () => {