为何全英文页面未通过AChecker的WCAG Check271双向文本检测？

Hey there, this is a super common head-scratcher—even fully English sites can fail this WCAG check, and the cause is often not obvious at first glance. Let’s walk through the most likely reasons why you’re seeing the "May need Unicode right-to-left mark or left-to-right mark" error:

• Hidden invisible bidirectional control characters
  Sometimes when copying content from documents, CMS platforms, or even other websites, you might accidentally bring along invisible Right-to-Left Mark (RLM, \u200F), Left-to-Right Mark (LRM, \u200E), or other bidirectional formatting characters. These don’t show up in your visual content, but AChecker’s scanner picks them up. Try enabling "show invisible characters" in your text editor (like VS Code’s Toggle Render Whitespace feature) or run a regex search for [\u200E\u200F\u202A-\u202E] in your HTML source to spot them.

• Third-party scripts or dynamic content
  Even if your core content is 100% English, third-party elements like ads, comment widgets, analytics scripts, or embedded tools might inject bidirectional characters behind the scenes. Some services add these markers to handle multilingual support automatically, even when it’s not needed for your site. Inspect your page’s full HTML source (using your browser’s DevTools) and search for the Unicode values mentioned above to track down these hidden characters.

• Potential false positive in AChecker
  While less common, automated accessibility tools can occasionally flag false positives. Cross-check your site with other WCAG validators like WAVE or axe DevTools. If those tools don’t report the same bidirectional text issue, it’s likely an error in AChecker’s scanning logic.

• Edge-case text combinations or HTML structure
  In rare cases, certain combinations of numbers, symbols, and text (even all English) might trigger the bidirectional algorithm unexpectedly. For example, strings with multiple hyphens, at symbols, or parentheses could be misinterpreted. Also, double-check if any elements have a dir attribute set to rtl or auto—even if you didn’t intentionally add it, a CMS or template might have included it somewhere.

Start with checking for hidden characters first—that’s the most frequent culprit here. If you don’t find any, move on to auditing third-party content or cross-validating with other tools.

内容的提问来源于stack exchange，提问作者Justin Case