Text Reverser

Features

• Four reversal modes
• Grapheme-aware, emoji and combining accents stay intact
• Automatic palindrome detection
• Feed the result back in with one click

How to use it

1. Type or paste your text.
2. Choose what to reverse: characters, words or lines.
3. The result updates immediately.
4. Copy it, or press Use result as input to reverse again.

Why reversing a string is harder than it looks

The obvious approach, str.split('').reverse().join(''): is subtly broken. JavaScript strings are sequences of UTF-16 code units, and any character outside the Basic Multilingual Plane occupies two of them. Splitting on code units tears those pairs apart, so reversing a string containing an emoji produces replacement characters instead of the emoji.

Combining marks cause a second problem. The letter é can be a single code point, or it can be a plain e followed by a combining acute accent. Reverse the second form naively and the accent detaches, landing on whatever character now precedes it. Flag emoji, skin-tone modifiers and family sequences are made of several code points joined by zero-width joiners and break the same way.

This tool uses Intl.Segmenter where the browser supports it, which splits text into grapheme clusters, what a reader would call a character, rather than code units. Where it is unavailable, it falls back to a code-point split, which at least keeps surrogate pairs together. That handles emoji correctly even if some exotic combining sequences still shift.