Text Reverser

What this tool is used for

• Reversing a string for a puzzle or a challenge.
• Reversing word order to check a palindrome by phrase rather than character.
• Flipping line order in a log to read newest first.
• Producing input to test a reversal implementation.
• Checking whether a phrase reads the same backwards.

Frequently Asked Questions

Why does reversing break emoji and accents?

Because naive reversal works on code units. An emoji is a surrogate pair in UTF-16, and reversing splits it into two invalid halves; a combining accent detaches from its letter and lands on the wrong one. Correct reversal works on grapheme clusters.

What is a grapheme cluster?

What a user perceives as one character, which may be several code points — a flag emoji, a family emoji, or e plus a combining acute. Unicode UAX #29 defines the boundaries, and Intl.Segmenter implements them.

What is the difference between reversing characters, words and lines?

Three distinct operations. Character reversal turns 'hello world' into 'dlrow olleh'; word reversal gives 'world hello'; line reversal reorders lines while leaving each intact. They are rarely interchangeable.

Does reversing help with palindromes?

Yes, that is the standard test — but a real check must first normalise: strip punctuation and spaces, and fold case. 'A man, a plan, a canal: Panama' is a palindrome only after that cleanup.

Does it work with right-to-left scripts?

The bytes reverse, but the result is usually meaningless. Arabic and Hebrew already display right to left through the bidirectional algorithm, so reversing the underlying order fights the renderer rather than mirroring the text.

What happens to combining marks when reversing?

They detach from their base and attach to whatever now precedes them, so `é` written as `e` plus an accent comes back with the accent on the wrong letter. Reversing by grapheme cluster is the only correct approach.

Why do reversed lines sometimes render out of order?

Because the bidirectional algorithm reorders text for display. Reversing a string containing Arabic or Hebrew produces something whose visual order is not the reverse of the original — the reordering happens after your change.

Common errors and gotchas

• Reversing by code unit, which splits emoji and combining sequences into broken fragments.
• Assuming character reversal and word reversal are the same operation.
• Reversing text with combining marks, where the mark ends up on the wrong base character.
• Reversing a right-to-left script, where display order and logical order already differ.
• Reversing lines in a file where the first line was a header.