Reverse a string

Reverse Unicode code points without splitting surrogate pairs.

JavaScript Version 1.0.0 · MIT · .md

function reverse(value) { return Array.from(value).reverse().join(''); }

Input & expected output

"code"

"edoc"

The edge case

"A😀B"

"B😀A"

Know the limits

• Combining marks and joined emoji can still split: code points are not grapheme clusters.
• For user-facing text, segment graphemes with Intl.Segmenter before reversing.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Capitalize a string — Uppercase the first Unicode code point and preserve the remaining text.
• Check a palindrome — Compare a string with its code-point reversal.
• Create a simple URL slug — Normalize a Latin-text label into lowercase ASCII words separated by hyphens.