Merge pull request #107 from darkriszty/bug/zero-width-chars

Handle the most probable zero-width characters

Author: darkriszty

CHANGELOG.md

@@ -5,6 +5,8 @@ All notable changes will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/) and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+### Fixed
+- Issue #106: Fixed table prettification breaking when cells contain zero-width characters.
 
 ## 4.0.0 - 2026-04-17
 ### Added

src/models/cell.ts

@@ -19,6 +19,10 @@ export class Cell {
     }
 
     private getCharDisplayLength(character: string): number {
+        // handle the most probable zero-width characters
+        if (/^[\u{200B}-\u{200F}\u{2060}-\u{2064}\u{FEFF}\u{034F}\u{061C}\u{00AD}]$/u.test(character))
+            return 0;
+
         // for the specified ranges use a length of 2, otherwise a length of 1
         return /^(([\u{4E00}-\u{9FFF}])|([\u{3400}-\u{4DBF}])|([\u{20000}-\u{2A6DF}])|([\u{2A700}-\u{2B73F}])|([\u{2B740}-\u{2B81F}]))$/u.test(character)
             ? 2

test/systemTests/resources/zeroWidthChars-expected.md

@@ -0,0 +1,19 @@
+| Syntax             | Example  | Expected behavior | Actual behavior  |
+|--------------------|----------|-------------------|------------------|
+| `@alice`           | @alice   | mention link      | mention link     |
+| `\@alice`          | \@alice  | no mention link   | **mention link** |
+| ``` `@alice` ```   | `@alice` | no mention link   | no mention link  |
+| `@​alice` with ZWSP | @​alice   | no mention link   | no mention link  |
+
+| Code   | Character Name            | Example | Purpose                             |
+|--------|---------------------------|---------|-------------------------------------|
+| U+200B | Zero Width Space          | ab​cd    | Invisible word boundary             |
+| U+200C | Zero Width Non-Joiner     | ab‌cd    | Prevents ligature joining           |
+| U+200D | Zero Width Joiner         | ab‍cd    | Joins characters into ligature      |
+| U+2060 | Word Joiner               | ab⁠cd    | Prevents line break                 |
+| U+2061 | Function Application      | ab⁡cd    | Invisible math operator             |
+| U+2062 | Invisible Times           | ab⁢cd    | Invisible multiplication sign       |
+| U+2063 | Invisible Separator       | ab⁣cd    | Invisible list separator            |
+| U+2064 | Invisible Plus            | ab⁤cd    | Invisible addition sign             |
+| U+034F | Combining Grapheme Joiner | ab͏cd    | Joins combining character sequences |
+| U+00AD | Soft Hyphen               | ab­cd    | Optional line-break hyphen          |

test/systemTests/resources/zeroWidthChars-input.md

@@ -0,0 +1,19 @@
+| Syntax              | Example  | Expected behavior | Actual behavior  |
+|---------------------|----------|-------------------|------------------|
+| `@alice`            | @alice   | mention link      | mention link     |
+| `\@alice`           | \@alice  | no mention link   | **mention link** |
+| ``` `@alice` ```    | `@alice` | no mention link   | no mention link  |
+| `@​alice` with ZWSP  | @​alice   | no mention link   | no mention link  |
+
+| Code | Character Name | Example | Purpose |
+|---|---|---|---|
+| U+200B | Zero Width Space | ab​cd | Invisible word boundary |
+| U+200C | Zero Width Non-Joiner | ab‌cd | Prevents ligature joining |
+| U+200D | Zero Width Joiner | ab‍cd | Joins characters into ligature |
+| U+2060 | Word Joiner | ab⁠cd | Prevents line break |
+| U+2061 | Function Application | ab⁡cd | Invisible math operator |
+| U+2062 | Invisible Times | ab⁢cd | Invisible multiplication sign |
+| U+2063 | Invisible Separator | ab⁣cd | Invisible list separator |
+| U+2064 | Invisible Plus | ab⁤cd | Invisible addition sign |
+| U+034F | Combining Grapheme Joiner | ab͏cd | Joins combining character sequences |
+| U+00AD | Soft Hyphen | ab­cd | Optional line-break hyphen |

test/unitTests/models/cell.test.ts

@@ -46,4 +46,16 @@ suite("Cell tests", () => {
     test("getLength() for specific CJK characters 3", () => {
         assert.strictEqual(new Cell("零件加工").getLength(), 8);
     });
+
+    test("getLength() for zero-width space returns 0", () => {
+        assert.strictEqual(new Cell("\u200B").getLength(), 0);
+    });
+
+    test("getLength() for text with zero-width space excludes it from length", () => {
+        assert.strictEqual(new Cell("@\alice").getLength(), 6);
+    });
+
+    test("getLength() for text with zero-width joiner excludes it from length", () => {
+        assert.strictEqual(new Cell("a\u200Db").getLength(), 2);
+    });
 });