Continue a markdown list on enter/return

When creating a list in markdown, when typing
return or enter at the end of a list item, create
a new empty list item.

app/assets/javascripts/lib/utils/text_markdown.js

@@ -5,6 +5,12 @@ import { insertText } from '~/lib/utils/common_utils';
 
 const LINK_TAG_PATTERN = '[{text}](url)';
 
+// at the start of a line, find any amount of whitespace followed by
+// a bullet point character (*+-) and an optional checkbox ([ ] [x])
+// OR a number with a . after it and an optional checkbox ([ ] [x])
+// followed by one or more whitespace characters
+const LIST_LINE_HEAD_PATTERN = /^(?<indent>\s*)(?<leader>((?<isOl>[*+-])|(?<isUl>\d+\.))( \[([x ])\])?\s)(?<content>.)?/;
+
 function selectedText(text, textarea) {
   return text.substring(textarea.selectionStart, textarea.selectionEnd);
 }
@@ -13,8 +19,15 @@ function addBlockTags(blockTag, selected) {
   return `${blockTag}\n${selected}\n${blockTag}`;
 }
 
-function lineBefore(text, textarea) {
-  const split = text.substring(0, textarea.selectionStart).trim().split('\n');
+function lineBefore(text, textarea, trimNewlines = true) {
+  let split = text.substring(0, textarea.selectionStart);
+
+  if (trimNewlines) {
+    split = split.trim();
+  }
+
+  split = split.split('\n');
+
   return split[split.length - 1];
 }
 
@@ -284,9 +297,9 @@ function updateText({ textArea, tag, cursorOffset, blockTag, wrap, select, tagCo
 }
 
 /* eslint-disable @gitlab/require-i18n-strings */
-export function keypressNoteText(e) {
+function handleSurroundSelectedText(e, textArea) {
   if (!gon.markdown_surround_selection) return;
-  if (this.selectionStart === this.selectionEnd) return;
+  if (textArea.selectionStart === textArea.selectionEnd) return;
 
   const keys = {
     '*': '**{text}**', // wraps with bold character
@@ -306,7 +319,7 @@ export function keypressNoteText(e) {
 
     updateText({
       tag,
-      textArea: this,
+      textArea,
       blockTag: '',
       wrap: true,
       select: '',
@@ -316,6 +329,48 @@ export function keypressNoteText(e) {
 }
 /* eslint-enable @gitlab/require-i18n-strings */
 
+function handleContinueList(e, textArea) {
+  if (!gon.features?.markdownContinueLists) return;
+  if (!(e.key === 'Enter')) return;
+  if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) return;
+  if (textArea.selectionStart !== textArea.selectionEnd) return;
+
+  const currentLine = lineBefore(textArea.value, textArea, false);
+  const result = currentLine.match(LIST_LINE_HEAD_PATTERN);
+
+  if (result) {
+    const { indent, content, leader } = result.groups;
+    const prevLineEmpty = !content;
+
+    if (prevLineEmpty) {
+      // erase previous empty list item - select the text and allow the
+      // natural line feed erase the text
+      textArea.selectionStart = textArea.selectionStart - result[0].length;
+      return;
+    }
+
+    const itemInsert = `${indent}${leader}`;
+
+    e.preventDefault();
+
+    updateText({
+      tag: itemInsert,
+      textArea,
+      blockTag: '',
+      wrap: false,
+      select: '',
+      tagContent: '',
+    });
+  }
+}
+
+export function keypressNoteText(e) {
+  const textArea = this;
+
+  handleContinueList(e, textArea);
+  handleSurroundSelectedText(e, textArea);
+}
+
 export function updateTextForToolbarBtn($toolbarBtn) {
   return updateText({
     textArea: $toolbarBtn.closest('.md-area').find('textarea'),

app/controllers/projects/issues_controller.rb

@@ -46,14 +46,15 @@ class Projects::IssuesController < Projects::ApplicationController
     push_frontend_feature_flag(:vue_issues_list, project&.group, default_enabled: :yaml)
     push_frontend_feature_flag(:iteration_cadences, project&.group, default_enabled: :yaml)
     push_frontend_feature_flag(:contacts_autocomplete, project&.group, default_enabled: :yaml)
+    push_frontend_feature_flag(:markdown_continue_lists, project, default_enabled: :yaml)
   end
 
   before_action only: :show do
-    push_frontend_feature_flag(:real_time_issue_sidebar, @project, default_enabled: :yaml)
+    push_frontend_feature_flag(:real_time_issue_sidebar, project, default_enabled: :yaml)
     push_frontend_feature_flag(:confidential_notes, project&.group, default_enabled: :yaml)
-    push_frontend_feature_flag(:issue_assignees_widget, @project, default_enabled: :yaml)
-    push_frontend_feature_flag(:paginated_issue_discussions, @project, default_enabled: :yaml)
-    push_frontend_feature_flag(:fix_comment_scroll, @project, default_enabled: :yaml)
+    push_frontend_feature_flag(:issue_assignees_widget, project, default_enabled: :yaml)
+    push_frontend_feature_flag(:paginated_issue_discussions, project, default_enabled: :yaml)
+    push_frontend_feature_flag(:fix_comment_scroll, project, default_enabled: :yaml)
     push_frontend_feature_flag(:work_items, project, default_enabled: :yaml)
   end
 

app/controllers/projects/merge_requests_controller.rb

@@ -36,20 +36,21 @@ class Projects::MergeRequestsController < Projects::MergeRequests::ApplicationCo
 
   before_action only: [:show] do
     push_frontend_feature_flag(:file_identifier_hash)
-    push_frontend_feature_flag(:merge_request_widget_graphql, @project, default_enabled: :yaml)
-    push_frontend_feature_flag(:default_merge_ref_for_diffs, @project, default_enabled: :yaml)
-    push_frontend_feature_flag(:core_security_mr_widget_counts, @project)
-    push_frontend_feature_flag(:paginated_notes, @project, default_enabled: :yaml)
-    push_frontend_feature_flag(:confidential_notes, @project, default_enabled: :yaml)
+    push_frontend_feature_flag(:merge_request_widget_graphql, project, default_enabled: :yaml)
+    push_frontend_feature_flag(:default_merge_ref_for_diffs, project, default_enabled: :yaml)
+    push_frontend_feature_flag(:core_security_mr_widget_counts, project)
+    push_frontend_feature_flag(:paginated_notes, project, default_enabled: :yaml)
+    push_frontend_feature_flag(:confidential_notes, project, default_enabled: :yaml)
     push_frontend_feature_flag(:improved_emoji_picker, project, default_enabled: :yaml)
     push_frontend_feature_flag(:restructured_mr_widget, project, default_enabled: :yaml)
-    push_frontend_feature_flag(:refactor_mr_widgets_extensions, @project, default_enabled: :yaml)
-    push_frontend_feature_flag(:rebase_without_ci_ui, @project, default_enabled: :yaml)
+    push_frontend_feature_flag(:refactor_mr_widgets_extensions, project, default_enabled: :yaml)
+    push_frontend_feature_flag(:rebase_without_ci_ui, project, default_enabled: :yaml)
     push_frontend_feature_flag(:rearrange_pipelines_table, project, default_enabled: :yaml)
+    push_frontend_feature_flag(:markdown_continue_lists, project, default_enabled: :yaml)
     # Usage data feature flags
-    push_frontend_feature_flag(:users_expanding_widgets_usage_data, @project, default_enabled: :yaml)
+    push_frontend_feature_flag(:users_expanding_widgets_usage_data, project, default_enabled: :yaml)
     push_frontend_feature_flag(:diff_settings_usage_data, default_enabled: :yaml)
-    push_frontend_feature_flag(:usage_data_diff_searches, @project, default_enabled: :yaml)
+    push_frontend_feature_flag(:usage_data_diff_searches, project, default_enabled: :yaml)
   end
 
   before_action do

config/feature_flags/development/markdown_continue_lists.yml

+---
+name: markdown_continue_lists
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/79161
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/351386
+milestone: '14.8'
+type: development
+group: group::project management
+default_enabled: false

spec/frontend/design_management/components/design_notes/design_reply_form_spec.js

@@ -31,6 +31,10 @@ describe('Design reply form component', () => {
     });
   }
 
+  beforeEach(() => {
+    gon.features = { markdownContinueLists: true };
+  });
+
   afterEach(() => {
     wrapper.destroy();
   });

spec/frontend/issues/show/components/fields/description_spec.js

@@ -25,6 +25,7 @@ describe('Description field component', () => {
 
   beforeEach(() => {
     jest.spyOn(eventHub, '$emit');
+    gon.features = { markdownContinueLists: true };
   });
 
   afterEach(() => {

spec/frontend/lib/utils/text_markdown_spec.js

@@ -165,6 +165,80 @@ describe('init markdown', () => {
         // cursor placement should be between tags
         expect(textArea.selectionStart).toBe(start.length + tag.length);
       });
+
+      describe('Continuing markdown lists', () => {
+        const enterEvent = new KeyboardEvent('keydown', { key: 'Enter' });
+
+        beforeEach(() => {
+          gon.features = { markdownContinueLists: true };
+        });
+
+        it.each`
+          text                           | expected
+          ${'- item'}                    | ${'- item\n- '}
+          ${'- [ ] item'}                | ${'- [ ] item\n- [ ] '}
+          ${'- [x] item'}                | ${'- [x] item\n- [x] '}
+          ${'- item\n  - second'}        | ${'- item\n  - second\n  - '}
+          ${'1. item'}                   | ${'1. item\n1. '}
+          ${'1. [ ] item'}               | ${'1. [ ] item\n1. [ ] '}
+          ${'1. [x] item'}               | ${'1. [x] item\n1. [x] '}
+          ${'108. item'}                 | ${'108. item\n108. '}
+          ${'108. item\n     - second'}  | ${'108. item\n     - second\n     - '}
+          ${'108. item\n     1. second'} | ${'108. item\n     1. second\n     1. '}
+        `('adds correct list continuation characters', ({ text, expected }) => {
+          textArea.value = text;
+          textArea.setSelectionRange(text.length, text.length);
+
+          textArea.addEventListener('keydown', keypressNoteText);
+          textArea.dispatchEvent(enterEvent);
+
+          expect(textArea.value).toEqual(expected);
+          expect(textArea.selectionStart).toBe(expected.length);
+        });
+
+        // test that when pressing Enter on an empty list item, the empty
+        // list item text is selected, so that when the Enter propagates,
+        // it's removed
+        it.each`
+          text                                     | expected
+          ${'- item\n- '}                          | ${'- item\n'}
+          ${'- [ ] item\n- [ ] '}                  | ${'- [ ] item\n'}
+          ${'- [x] item\n- [x] '}                  | ${'- [x] item\n'}
+          ${'- item\n  - second\n  - '}            | ${'- item\n  - second\n'}
+          ${'1. item\n1. '}                        | ${'1. item\n'}
+          ${'1. [ ] item\n1. [ ] '}                | ${'1. [ ] item\n'}
+          ${'1. [x] item\n1. [x] '}                | ${'1. [x] item\n'}
+          ${'108. item\n108. '}                    | ${'108. item\n'}
+          ${'108. item\n     - second\n     - '}   | ${'108. item\n     - second\n'}
+          ${'108. item\n     1. second\n     1. '} | ${'108. item\n     1. second\n'}
+        `('adds correct list continuation characters', ({ text, expected }) => {
+          textArea.value = text;
+          textArea.setSelectionRange(text.length, text.length);
+
+          textArea.addEventListener('keydown', keypressNoteText);
+          textArea.dispatchEvent(enterEvent);
+
+          expect(textArea.value.substr(0, textArea.selectionStart)).toEqual(expected);
+          expect(textArea.selectionStart).toBe(expected.length);
+          expect(textArea.selectionEnd).toBe(text.length);
+        });
+
+        it('does nothing if feature flag disabled', () => {
+          gon.features = { markdownContinueLists: false };
+
+          const text = '- item';
+          const expected = '- item';
+
+          textArea.value = text;
+          textArea.setSelectionRange(text.length, text.length);
+
+          textArea.addEventListener('keydown', keypressNoteText);
+          textArea.dispatchEvent(enterEvent);
+
+          expect(textArea.value).toEqual(expected);
+          expect(textArea.selectionStart).toBe(expected.length);
+        });
+      });
     });
 
     describe('with selection', () => {

spec/frontend/notes/components/note_form_spec.js

@@ -45,6 +45,8 @@ describe('issue_note_form component', () => {
       noteBody: 'Magni suscipit eius consectetur enim et ex et commodi.',
       noteId: '545',
     };
+
+    gon.features = { markdownContinueLists: true };
   });
 
   afterEach(() => {

spec/frontend/vue_shared/issuable/show/components/issuable_edit_form_spec.js

@@ -36,6 +36,7 @@ describe('IssuableEditForm', () => {
 
   beforeEach(() => {
     wrapper = createComponent();
+    gon.features = { markdownContinueLists: true };
   });
 
   afterEach(() => {

spec/frontend/zen_mode_spec.js

@@ -45,6 +45,8 @@ describe('ZenMode', () => {
 
     // Set this manually because we can't actually scroll the window
     zen.scroll_position = 456;
+
+    gon.features = { markdownContinueLists: true };
   });
 
   describe('enabling dropzone', () => {

spec/support/shared_examples/features/wiki/user_previews_wiki_changes_shared_examples.rb

@@ -85,7 +85,9 @@ RSpec.shared_examples 'User previews wiki changes' do
     end
 
     it 'renders content with CommonMark' do
-      fill_in :wiki_content, with: "1. one\n  - sublist\n"
+      # using two `\n` ensures we're sublist to it's own line due
+      # to list auto-continue
+      fill_in :wiki_content, with: "1. one\n\n  - sublist\n"
       click_on "Preview"
 
       # the above generates two separate lists (not embedded) in CommonMark