Branch off the Live Preview into a separate extension

app/assets/javascripts/editor/extensions/source_editor_markdown_ext.js

-import { debounce } from 'lodash';
-import { BLOB_PREVIEW_ERROR } from '~/blob_edit/constants';
-import createFlash from '~/flash';
-import { sanitize } from '~/lib/dompurify';
-import axios from '~/lib/utils/axios_utils';
-import { __ } from '~/locale';
-import syntaxHighlight from '~/syntax_highlight';
-import {
-  EXTENSION_MARKDOWN_PREVIEW_PANEL_CLASS,
-  EXTENSION_MARKDOWN_PREVIEW_ACTION_ID,
-  EXTENSION_MARKDOWN_PREVIEW_PANEL_WIDTH,
-  EXTENSION_MARKDOWN_PREVIEW_PANEL_PARENT_CLASS,
-  EXTENSION_MARKDOWN_PREVIEW_UPDATE_DELAY,
-} from '../constants';
-import { SourceEditorExtension } from './source_editor_extension_base';
-
-const getPreview = (text, previewMarkdownPath) => {
-  return axios
-    .post(previewMarkdownPath, {
-      text,
-    })
-    .then(({ data }) => {
-      return data.body;
-    });
-};
-
-const setupDomElement = ({ injectToEl = null } = {}) => {
-  const previewEl = document.createElement('div');
-  previewEl.classList.add(EXTENSION_MARKDOWN_PREVIEW_PANEL_CLASS);
-  previewEl.style.display = 'none';
-  if (injectToEl) {
-    injectToEl.appendChild(previewEl);
-  }
-  return previewEl;
-};
-
-export class EditorMarkdownExtension extends SourceEditorExtension {
-  constructor({ instance, previewMarkdownPath, ...args } = {}) {
-    super({ instance, ...args });
-    Object.assign(instance, {
-      previewMarkdownPath,
-      preview: {
-        el: undefined,
-        action: undefined,
-        shown: false,
-        modelChangeListener: undefined,
-      },
-    });
-    this.setupPreviewAction.call(instance);
-
-    instance.getModel().onDidChangeLanguage(({ newLanguage, oldLanguage } = {}) => {
-      if (newLanguage === 'markdown' && oldLanguage !== newLanguage) {
-        instance.setupPreviewAction();
-      } else {
-        instance.cleanup();
-      }
-    });
-
-    instance.onDidChangeModel(() => {
-      const model = instance.getModel();
-      if (model) {
-        const { language } = model.getLanguageIdentifier();
-        instance.cleanup();
-        if (language === 'markdown') {
-          instance.setupPreviewAction();
-        }
-      }
-    });
-  }
-
-  static togglePreviewLayout() {
-    const { width, height } = this.getLayoutInfo();
-    const newWidth = this.preview.shown
-      ? width / EXTENSION_MARKDOWN_PREVIEW_PANEL_WIDTH
-      : width * EXTENSION_MARKDOWN_PREVIEW_PANEL_WIDTH;
-    this.layout({ width: newWidth, height });
-  }
-
-  static togglePreviewPanel() {
-    const parentEl = this.getDomNode().parentElement;
-    const { el: previewEl } = this.preview;
-    parentEl.classList.toggle(EXTENSION_MARKDOWN_PREVIEW_PANEL_PARENT_CLASS);
-
-    if (previewEl.style.display === 'none') {
-      // Show the preview panel
-      this.fetchPreview();
-    } else {
-      // Hide the preview panel
-      previewEl.style.display = 'none';
-    }
-  }
-
-  cleanup() {
-    if (this.preview.modelChangeListener) {
-      this.preview.modelChangeListener.dispose();
-    }
-    this.preview.action.dispose();
-    if (this.preview.shown) {
-      EditorMarkdownExtension.togglePreviewPanel.call(this);
-      EditorMarkdownExtension.togglePreviewLayout.call(this);
-    }
-    this.preview.shown = false;
-  }
-
-  fetchPreview() {
-    const { el: previewEl } = this.preview;
-    getPreview(this.getValue(), this.previewMarkdownPath)
-      .then((data) => {
-        previewEl.innerHTML = sanitize(data);
-        syntaxHighlight(previewEl.querySelectorAll('.js-syntax-highlight'));
-        previewEl.style.display = 'block';
-      })
-      .catch(() => createFlash(BLOB_PREVIEW_ERROR));
-  }
-
-  setupPreviewAction() {
-    if (this.getAction(EXTENSION_MARKDOWN_PREVIEW_ACTION_ID)) return;
-
-    this.preview.action = this.addAction({
-      id: EXTENSION_MARKDOWN_PREVIEW_ACTION_ID,
-      label: __('Preview Markdown'),
-      keybindings: [
-        // eslint-disable-next-line no-bitwise,no-undef
-        monaco.KeyMod.chord(monaco.KeyMod.CtrlCmd | monaco.KeyMod.Shift | monaco.KeyCode.KEY_P),
-      ],
-      contextMenuGroupId: 'navigation',
-      contextMenuOrder: 1.5,
-
-      // Method that will be executed when the action is triggered.
-      // @param ed The editor instance is passed in as a convenience
-      run(instance) {
-        instance.togglePreview();
-      },
-    });
-  }
-
-  togglePreview() {
-    if (!this.preview?.el) {
-      this.preview.el = setupDomElement({ injectToEl: this.getDomNode().parentElement });
-    }
-    EditorMarkdownExtension.togglePreviewLayout.call(this);
-    EditorMarkdownExtension.togglePreviewPanel.call(this);
-
-    if (!this.preview?.shown) {
-      this.preview.modelChangeListener = this.onDidChangeModelContent(
-        debounce(this.fetchPreview.bind(this), EXTENSION_MARKDOWN_PREVIEW_UPDATE_DELAY),
-      );
-    } else {
-      this.preview.modelChangeListener.dispose();
-    }
-
-    this.preview.shown = !this.preview?.shown;
-  }
+import { EditorMarkdownPreviewExtension } from '~/editor/extensions/source_editor_markdown_livepreview_ext';
 
+export class EditorMarkdownExtension extends EditorMarkdownPreviewExtension {
   getSelectedText(selection = this.getSelection()) {
     const { startLineNumber, endLineNumber, startColumn, endColumn } = selection;
     const valArray = this.getValue().split('\n');

app/assets/javascripts/editor/extensions/source_editor_markdown_livepreview_ext.js

+import { debounce } from 'lodash';
+import { BLOB_PREVIEW_ERROR } from '~/blob_edit/constants';
+import createFlash from '~/flash';
+import { sanitize } from '~/lib/dompurify';
+import axios from '~/lib/utils/axios_utils';
+import { __ } from '~/locale';
+import syntaxHighlight from '~/syntax_highlight';
+import {
+  EXTENSION_MARKDOWN_PREVIEW_PANEL_CLASS,
+  EXTENSION_MARKDOWN_PREVIEW_ACTION_ID,
+  EXTENSION_MARKDOWN_PREVIEW_PANEL_WIDTH,
+  EXTENSION_MARKDOWN_PREVIEW_PANEL_PARENT_CLASS,
+  EXTENSION_MARKDOWN_PREVIEW_UPDATE_DELAY,
+} from '../constants';
+import { SourceEditorExtension } from './source_editor_extension_base';
+
+const getPreview = (text, previewMarkdownPath) => {
+  return axios
+    .post(previewMarkdownPath, {
+      text,
+    })
+    .then(({ data }) => {
+      return data.body;
+    });
+};
+
+const setupDomElement = ({ injectToEl = null } = {}) => {
+  const previewEl = document.createElement('div');
+  previewEl.classList.add(EXTENSION_MARKDOWN_PREVIEW_PANEL_CLASS);
+  previewEl.style.display = 'none';
+  if (injectToEl) {
+    injectToEl.appendChild(previewEl);
+  }
+  return previewEl;
+};
+
+export class EditorMarkdownPreviewExtension extends SourceEditorExtension {
+  constructor({ instance, previewMarkdownPath, ...args } = {}) {
+    super({ instance, ...args });
+    Object.assign(instance, {
+      previewMarkdownPath,
+      preview: {
+        el: undefined,
+        action: undefined,
+        shown: false,
+        modelChangeListener: undefined,
+      },
+    });
+    this.setupPreviewAction.call(instance);
+
+    instance.getModel().onDidChangeLanguage(({ newLanguage, oldLanguage } = {}) => {
+      if (newLanguage === 'markdown' && oldLanguage !== newLanguage) {
+        instance.setupPreviewAction();
+      } else {
+        instance.cleanup();
+      }
+    });
+
+    instance.onDidChangeModel(() => {
+      const model = instance.getModel();
+      if (model) {
+        const { language } = model.getLanguageIdentifier();
+        instance.cleanup();
+        if (language === 'markdown') {
+          instance.setupPreviewAction();
+        }
+      }
+    });
+  }
+
+  static togglePreviewLayout() {
+    const { width, height } = this.getLayoutInfo();
+    const newWidth = this.preview.shown
+      ? width / EXTENSION_MARKDOWN_PREVIEW_PANEL_WIDTH
+      : width * EXTENSION_MARKDOWN_PREVIEW_PANEL_WIDTH;
+    this.layout({ width: newWidth, height });
+  }
+
+  static togglePreviewPanel() {
+    const parentEl = this.getDomNode().parentElement;
+    const { el: previewEl } = this.preview;
+    parentEl.classList.toggle(EXTENSION_MARKDOWN_PREVIEW_PANEL_PARENT_CLASS);
+
+    if (previewEl.style.display === 'none') {
+      // Show the preview panel
+      this.fetchPreview();
+    } else {
+      // Hide the preview panel
+      previewEl.style.display = 'none';
+    }
+  }
+
+  cleanup() {
+    if (this.preview.modelChangeListener) {
+      this.preview.modelChangeListener.dispose();
+    }
+    this.preview.action.dispose();
+    if (this.preview.shown) {
+      EditorMarkdownPreviewExtension.togglePreviewPanel.call(this);
+      EditorMarkdownPreviewExtension.togglePreviewLayout.call(this);
+    }
+    this.preview.shown = false;
+  }
+
+  fetchPreview() {
+    const { el: previewEl } = this.preview;
+    getPreview(this.getValue(), this.previewMarkdownPath)
+      .then((data) => {
+        previewEl.innerHTML = sanitize(data);
+        syntaxHighlight(previewEl.querySelectorAll('.js-syntax-highlight'));
+        previewEl.style.display = 'block';
+      })
+      .catch(() => createFlash(BLOB_PREVIEW_ERROR));
+  }
+
+  setupPreviewAction() {
+    if (this.getAction(EXTENSION_MARKDOWN_PREVIEW_ACTION_ID)) return;
+
+    this.preview.action = this.addAction({
+      id: EXTENSION_MARKDOWN_PREVIEW_ACTION_ID,
+      label: __('Preview Markdown'),
+      keybindings: [
+        // eslint-disable-next-line no-bitwise,no-undef
+        monaco.KeyMod.chord(monaco.KeyMod.CtrlCmd | monaco.KeyMod.Shift | monaco.KeyCode.KEY_P),
+      ],
+      contextMenuGroupId: 'navigation',
+      contextMenuOrder: 1.5,
+
+      // Method that will be executed when the action is triggered.
+      // @param ed The editor instance is passed in as a convenience
+      run(instance) {
+        instance.togglePreview();
+      },
+    });
+  }
+
+  togglePreview() {
+    if (!this.preview?.el) {
+      this.preview.el = setupDomElement({ injectToEl: this.getDomNode().parentElement });
+    }
+    EditorMarkdownPreviewExtension.togglePreviewLayout.call(this);
+    EditorMarkdownPreviewExtension.togglePreviewPanel.call(this);
+
+    if (!this.preview?.shown) {
+      this.preview.modelChangeListener = this.onDidChangeModelContent(
+        debounce(this.fetchPreview.bind(this), EXTENSION_MARKDOWN_PREVIEW_UPDATE_DELAY),
+      );
+    } else {
+      this.preview.modelChangeListener.dispose();
+    }
+
+    this.preview.shown = !this.preview?.shown;
+  }
+}