Removed dependency on $ from the highlighter

Changelog: changed
MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/67771

app/assets/javascripts/behaviors/markdown/render_gfm.js

@@ -11,7 +11,7 @@ import renderMetrics from './render_metrics';
 // Delegates to syntax highlight and render math & mermaid diagrams.
 //
 $.fn.renderGFM = function renderGFM() {
-  syntaxHighlight(this.find('.js-syntax-highlight'));
+  syntaxHighlight(this.find('.js-syntax-highlight').get());
   renderMath(this.find('.js-render-math'));
   renderMermaid(this.find('.js-render-mermaid'));
   highlightCurrentUser(this.find('.gfm-project_member').get());

app/assets/javascripts/syntax_highlight.js

 /* eslint-disable consistent-return */
 
-import $ from 'jquery';
-
 // Syntax Highlighter
 //
 // Applies a syntax highlighting color scheme CSS class to any element with the
@@ -12,14 +10,30 @@ import $ from 'jquery';
 //   <div class="js-syntax-highlight"></div>
 //
 
-export default function syntaxHighlight(el) {
-  if ($(el).hasClass('js-syntax-highlight')) {
-    // Given the element itself, apply highlighting
-    return $(el).addClass(gon.user_color_scheme);
-  }
-  // Given a parent element, recurse to any of its applicable children
-  const $children = $(el).find('.js-syntax-highlight');
-  if ($children.length) {
-    return syntaxHighlight($children);
+export default function syntaxHighlight($els = null) {
+  if (!$els) return;
+
+  const els = $els.get ? $els.get() : $els;
+  const handler = (el) => {
+    if (el.classList.contains('js-syntax-highlight')) {
+      // Given the element itself, apply highlighting
+      return el.classList.add(gon.user_color_scheme);
+    }
+    // Given a parent element, recurse to any of its applicable children
+    const children = el.querySelectorAll('.js-syntax-highlight');
+    if (children.length) {
+      return syntaxHighlight(children);
+    }
+  };
+
+  // In order to account for NodeList returned by document.querySelectorAll,
+  // we should rather check whether the els object is iterable
+  // instead of relying on Array.isArray()
+  const isIterable = typeof els[Symbol.iterator] === 'function';
+
+  if (isIterable) {
+    els.forEach((el) => handler(el));
+  } else {
+    handler(els);
   }
 }

spec/frontend/syntax_highlight_spec.js

@@ -10,39 +10,50 @@ describe('Syntax Highlighter', () => {
     }
     return (window.gon.user_color_scheme = value);
   };
-  describe('on a js-syntax-highlight element', () => {
-    beforeEach(() => {
-      setFixtures('<div class="js-syntax-highlight"></div>');
-    });
-
-    it('applies syntax highlighting', () => {
-      stubUserColorScheme('monokai');
-      syntaxHighlight($('.js-syntax-highlight'));
 
-      expect($('.js-syntax-highlight')).toHaveClass('monokai');
+  // We have to bind `document.querySelectorAll` to `document` to not mess up the fn's context
+  describe.each`
+    desc                | fn
+    ${'jquery'}         | ${$}
+    ${'vanilla all'}    | ${document.querySelectorAll.bind(document)}
+    ${'vanilla single'} | ${document.querySelector.bind(document)}
+  `('highlight using $desc syntax', ({ fn }) => {
+    describe('on a js-syntax-highlight element', () => {
+      beforeEach(() => {
+        setFixtures('<div class="js-syntax-highlight"></div>');
+      });
+
+      it('applies syntax highlighting', () => {
+        stubUserColorScheme('monokai');
+        syntaxHighlight(fn('.js-syntax-highlight'));
+
+        expect(fn('.js-syntax-highlight')).toHaveClass('monokai');
+      });
     });
-  });
 
-  describe('on a parent element', () => {
-    beforeEach(() => {
-      setFixtures(
-        '<div class="parent">\n  <div class="js-syntax-highlight"></div>\n  <div class="foo"></div>\n  <div class="js-syntax-highlight"></div>\n</div>',
-      );
-    });
+    describe('on a parent element', () => {
+      beforeEach(() => {
+        setFixtures(
+          '<div class="parent">\n  <div class="js-syntax-highlight"></div>\n  <div class="foo"></div>\n  <div class="js-syntax-highlight"></div>\n</div>',
+        );
+      });
 
-    it('applies highlighting to all applicable children', () => {
-      stubUserColorScheme('monokai');
-      syntaxHighlight($('.parent'));
+      it('applies highlighting to all applicable children', () => {
+        stubUserColorScheme('monokai');
+        syntaxHighlight(fn('.parent'));
 
-      expect($('.parent, .foo')).not.toHaveClass('monokai');
-      expect($('.monokai').length).toBe(2);
-    });
+        expect(fn('.parent')).not.toHaveClass('monokai');
+        expect(fn('.foo')).not.toHaveClass('monokai');
+
+        expect(document.querySelectorAll('.monokai').length).toBe(2);
+      });
 
-    it('prevents an infinite loop when no matches exist', () => {
-      setFixtures('<div></div>');
-      const highlight = () => syntaxHighlight($('div'));
+      it('prevents an infinite loop when no matches exist', () => {
+        setFixtures('<div></div>');
+        const highlight = () => syntaxHighlight(fn('div'));
 
-      expect(highlight).not.toThrow();
+        expect(highlight).not.toThrow();
+      });
     });
   });
 });