fix: prevent single-tilde strikethrough false positives (#3910)

diadorer · Nikita Barinov · UziTech · web-flow · commit 5e03369db410 · 2026-03-20T09:06:48.000-06:00
Co-authored-by: Nikita Barinov &lt;diadorer@nebius.com&gt;
Co-authored-by: Tony Brix &lt;tony@brix.ninja&gt;
diff --git a/src/rules.ts b/src/rules.ts
@@ -277,11 +277,6 @@ const _punctuationGfmStrongEm = /(?!~)[\p{P}\p{S}]/u;
 const _punctuationOrSpaceGfmStrongEm = /(?!~)[\s\p{P}\p{S}]/u;
 const _notPunctuationOrSpaceGfmStrongEm = /(?:[^\s\p{P}\p{S}]|~)/u;
 
-// GFM allows * and _ inside strikethrough
-const _punctuationGfmDel = /(?![*_])[\p{P}\p{S}]/u;
-const _punctuationOrSpaceGfmDel = /(?![*_])[\s\p{P}\p{S}]/u;
-const _notPunctuationOrSpaceGfmDel = /(?:[^\s\p{P}\p{S}]|[*_])/u;
-
 // sequences em should skip over [title](link), `code`, <html>
 const blockSkip = edit(/link|precode-code|html/, 'g')
   .replace('link', /\[(?:[^\[\]`]|(?<a>`+)[^`]+\k<a>(?!`))*?\]\((?:\\[\s\S]|[^\\\(\)]|\((?:\\[\s\S]|[^\\\(\)])*\))*\)/)
@@ -338,7 +333,7 @@ const emStrongRDelimUnd = edit(
 
 // Tilde left delimiter for strikethrough (similar to emStrongLDelim for asterisk)
 const delLDelim = edit(/^~~?(?:((?!~)punct)|[^\s~])/, 'u')
-  .replace(/punct/g, _punctuationGfmDel)
+  .replace(/punct/g, _punctuation)
   .getRegex();
 
 // Tilde delimiter patterns for strikethrough (similar to asterisk)
@@ -352,9 +347,9 @@ const delRDelimCore =
 + '|notPunctSpace(~~?)(?=notPunctSpace)'; // (6) a~~a can be either Left or Right Delimiter
 
 const delRDelim = edit(delRDelimCore, 'gu')
-  .replace(/notPunctSpace/g, _notPunctuationOrSpaceGfmDel)
-  .replace(/punctSpace/g, _punctuationOrSpaceGfmDel)
-  .replace(/punct/g, _punctuationGfmDel)
+  .replace(/notPunctSpace/g, _notPunctuationOrSpace)
+  .replace(/punctSpace/g, _punctuationOrSpace)
+  .replace(/punct/g, _punctuation)
   .getRegex();
 
 const anyPunctuation = edit(/\\(punct)/, 'gu')
diff --git a/test/specs/new/del_flanking.html b/test/specs/new/del_flanking.html
@@ -3,3 +3,5 @@
 <p>Between (~1.34) and (~5.4)</p>
 <p>~ test~</p>
 <p>~test ~</p>
+<p>The mass of the Higgs boson is ~125 GeV, while the top quark is <strong>~173 GeV</strong></p>
+<p>~~1 <strong>~~2</strong></p>
diff --git a/test/specs/new/del_flanking.md b/test/specs/new/del_flanking.md
@@ -7,3 +7,7 @@ Between (~1.34) and (~5.4)
 ~ test~
 
 ~test ~
+
+The mass of the Higgs boson is ~125 GeV, while the top quark is **~173 GeV**
+
+~~1 **~~2**
diff --git a/test/specs/new/del_strikethrough.html b/test/specs/new/del_strikethrough.html
@@ -13,4 +13,8 @@
 
 <p>test~~</p>
 
+<p><del>1  a</del>2</p>
+
+<p><del>1  a</del>2</p>
+
 <pre><code class="language-test~~~"></code></pre>
diff --git a/test/specs/new/del_strikethrough.md b/test/specs/new/del_strikethrough.md
@@ -13,4 +13,8 @@ test~~
 
 test~~
 
+~1  a~2
+
+~~1  a~~2
+
 ~~~test~~~
