Support extension-less links in the markdown preview

Fixes #39945

extensions/markdown/media/main.js

@@ -2,7 +2,7 @@
  *  Copyright (c) Microsoft Corporation. All rights reserved.
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
-
+// @ts-check
 'use strict';
 
 (function () {
@@ -29,6 +29,13 @@
 		};
 	}
 
+	function postMessage(command, args) {
+		window.parent.postMessage({
+			command: 'did-click-link',
+			data: `command:${command}?${encodeURIComponent(JSON.stringify(args))}`
+		}, 'file://');
+	}
+
 	/**
 	 * Find the html elements that map to a specific target line in the editor.
 	 *
@@ -196,14 +203,34 @@
 		const offset = event.pageY;
 		const line = getEditorLineNumberForPageOffset(offset);
 		if (!isNaN(line)) {
-			const args = [settings.source, line];
-			window.parent.postMessage({
-				command: "did-click-link",
-				data: `command:_markdown.didClick?${encodeURIComponent(JSON.stringify(args))}`
-			}, "file://");
+			postMessage('_markdown.didClick', [settings.source, line]);
 		}
 	});
 
+	document.addEventListener('click', event => {
+		if (!event) {
+			return;
+		}
+
+		const baseElement = document.getElementsByTagName('base')[0];
+
+		/** @type {any} */
+		let node = event.target;
+		while (node) {
+			if (node.tagName && node.tagName.toLowerCase() === 'a' && node.href) {
+				if (node.href.startsWith('file://')) {
+					const [path, frag] = node.href.replace(/^file:\/\//i, '').split('#');
+					postMessage('_markdown.openDocumentLink', { path, frag });
+					event.preventDefault();
+					event.stopPropagation();
+					break;
+				}
+				break;
+			}
+			node = node.parentNode;
+		}
+	}, true);
+
 	if (settings.scrollEditorWithPreview) {
 		window.addEventListener('scroll', throttle(() => {
 			if (scrollDisabled) {
@@ -211,11 +238,7 @@
 			} else {
 				const line = getEditorLineNumberForPageOffset(window.scrollY);
 				if (!isNaN(line)) {
-					const args = [settings.source, line];
-					window.parent.postMessage({
-						command: 'did-click-link',
-						data: `command:_markdown.revealLine?${encodeURIComponent(JSON.stringify(args))}`
-					}, 'file://');
+					postMessage('_markdown.revealLine', [settings.source, line]);
 				}
 			}
 		}, 50));

extensions/markdown/src/markdownEngine.ts

@@ -137,8 +137,9 @@ export class MarkdownEngine {
 		md.normalizeLink = (link: string) => {
 			try {
 				let uri = vscode.Uri.parse(link);
-				if (!uri.scheme && uri.path && !uri.fragment) {
+				if (!uri.scheme && uri.path) {
 					// Assume it must be a file
+					const fragment = uri.fragment;
 					if (uri.path[0] === '/') {
 						const root = vscode.workspace.getWorkspaceFolder(this.currentDocument);
 						if (root) {
@@ -147,6 +148,10 @@ export class MarkdownEngine {
 					} else {
 						uri = vscode.Uri.file(path.join(path.dirname(this.currentDocument.path), uri.path));
 					}
+
+					if (fragment) {
+						uri = uri.with({ fragment });
+					}
 					return normalizeLink(uri.toString(true));
 				}
 			} catch (e) {

src/vs/workbench/parts/html/browser/webview-pre.js

@@ -46,11 +46,12 @@
 		if (!event || !event.view || !event.view.document) {
 			return;
 		}
+
+		var baseElement = event.view.document.getElementsByTagName('base')[0];
 		/** @type {any} */
 		var node = event.target;
 		while (node) {
 			if (node.tagName && node.tagName.toLowerCase() === 'a' && node.href) {
-				var baseElement = event.view.document.getElementsByTagName('base')[0];
 				if (node.getAttribute('href') === '#') {
 					event.view.scrollTo(0, 0);
 				} else if (node.hash && (node.getAttribute('href') === node.hash || (baseElement && node.href.indexOf(baseElement.href) >= 0))) {