From 4bb767f8eec65b99066d0351824c050a5bc4b4c6 Mon Sep 17 00:00:00 2001
From: Elian Doran <contact@eliandoran.me>
Date: Sat, 5 Apr 2025 10:46:33 +0300
Subject: [PATCH] fix(import/markdown): preserve escaped math expressions

---
 src/services/import/markdown.spec.ts | 10 ++++++++++
 src/services/import/markdown.ts      |  7 +++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/services/import/markdown.spec.ts b/src/services/import/markdown.spec.ts
index d2d8ea694..e25a8bc09 100644
--- a/src/services/import/markdown.spec.ts
+++ b/src/services/import/markdown.spec.ts
@@ -175,4 +175,14 @@ second line 2</code></pre><ul><li>Hello</li><li>world</li></ul><ol><li>Hello</li
         expect(markdownService.renderToHtml(input, "Title")).toStrictEqual(expected);
     });
 
+    it("preserves escaped math expressions", () => {
+        const scenarios = [
+            "\\$\\$\sqrt{x^{2}+1}\\$\\$",
+            "The equation is \\$e=mc^{2}\\$."
+        ];
+        for (const scenario of scenarios) {
+            expect(markdownService.renderToHtml(scenario, "Title")).toStrictEqual(`<p>${scenario}</p>`);
+        }
+    });
+
 });
diff --git a/src/services/import/markdown.ts b/src/services/import/markdown.ts
index 60f770bbd..209d4afe5 100644
--- a/src/services/import/markdown.ts
+++ b/src/services/import/markdown.ts
@@ -16,11 +16,11 @@ class CustomMarkdownRenderer extends Renderer {
 
         if (text.includes("$")) {
             // Display math
-            text = text.replaceAll(/\$\$(.+)\$\$/g,
+            text = text.replaceAll(/(?<!\\)\$\$(.+)\$\$/g,
                 `<span class="math-tex">\\\[$1\\\]</span>`);
 
             // Inline math
-            text = text.replaceAll(/\$(.+)\$/g,
+            text = text.replaceAll(/(?<!\\)\$(.+)\$/g,
                 `<span class="math-tex">\\\($1\\\)</span>`);
         }
 
@@ -87,6 +87,9 @@ import { ADMONITION_TYPE_MAPPINGS } from "../export/markdown.js";
 import utils from "../utils.js";
 
 function renderToHtml(content: string, title: string) {
+    // Double-escape slashes in math expression because they are otherwise consumed by the parser somewhere.
+    content = content.replaceAll("\\$", "\\\\$");
+
     let html = parse(content, {
         async: false,
         renderer: renderer