Simon Willison’s Weblog

15th March 2009 - Link Blog

Understanding Bidirectional (BIDI) Text in Unicode. It turns out you need to sanitise user input to ensure there are no unicode characters that switch your site’s regular text to RTL.

Posted 15th March 2009 at 4:37 am

Recent articles

Writing about Agentic Engineering Patterns - 23rd February 2026
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This is a link post by Simon Willison, posted on 15th March 2009.

bidi 1 cal-henderson 7 filtering 2 security 575 unicode 29 userinput 1

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