Set target="_blank" for external links

lib/banzai/filter/external_link_filter.rb

@@ -15,6 +15,9 @@ def call
           next if link.start_with?(internal_url)
 
           node.set_attribute('rel', 'nofollow noreferrer')
+
+          # Open external links on a new tab
+          node.set_attribute('target', '_blank')
         end
 
         doc

spec/features/markdown_spec.rb

@@ -173,10 +173,20 @@ def doc(html = @html)
         expect(link.attr('rel')).to include('noreferrer')
       end
 
+      it 'adds _blank to target attribute for external links' do
+        link = doc.at_css('a:contains("Google")')
+        expect(link.attr('target')).to match('_blank')
+      end
+
       it 'ignores internal link' do
         link = doc.at_css('a:contains("GitLab Root")')
         expect(link.attr('rel')).not_to match 'nofollow'
       end
+
+      it 'does not set _blank to target attribute for internal links' do
+        link = doc.at_css('a:contains("GitLab Root")')
+        expect(link.attr('target')).not_to match '_blank'
+      end
     end
   end
 

spec/fixtures/markdown.md.erb

@@ -136,7 +136,7 @@ But it shouldn't autolink text inside certain tags:
 
 ### ExternalLinkFilter
 
-External links get a `rel="nofollow"` attribute:
+External links get a `rel="nofollow noreferrer"` and `target="_blank"` attributes:
 
 - [Google](https://google.com/)
 - [GitLab Root](<%= Gitlab.config.gitlab.url %>)