How to Reverse a String in JavaScript, Python and PHP

Reversing a string is a common programming exercise, and a surprisingly good test of how well you understand text encoding.

JavaScript

The simple version:

const reversed = str.split('').reverse().join('');

This breaks emoji and some symbols, because split('') splits by UTF-16 code units, and many emoji use two. A better version uses the string iterator:

const reversed = [...str].reverse().join('');

For full correctness with combined characters (such as flags, skin-tone emoji or letters with separate accent marks), use Intl.Segmenter:

const seg = new Intl.Segmenter(undefined, { granularity: 'grapheme' });
const reversed = [...seg.segment(str)].map(s => s.segment).reverse().join('');

Python

reversed_text = text[::-1]

Python slices by Unicode code points, which handles most text but can still separate combining marks and multi-part emoji. Libraries such as grapheme or the regex module's \X pattern can split by grapheme clusters.

PHP

strrev() works only on single-byte strings and corrupts multi-byte UTF-8 text such as "café". A safer approach:

$reversed = implode('', array_reverse(mb_str_split($text)));

mb_str_split() is available from PHP 7.4.

Reversing words instead of characters

// JavaScript
const reversedWords = str.split(/\s+/).reverse().join(' ');

Try it without code

The NS Tools Hub reverse text generator uses grapheme-aware reversing, so you can compare your function's output with a correct result for tricky test strings.

Frequently asked questions

How to reverse a string in Python?

To reverse a string in Python, use slicing: text[::-1]. For text with combining accents or complex emoji, split it into grapheme clusters first with a library.

How to reverse a string in PHP?

To reverse a string in PHP safely, use implode('', array_reverse(mb_str_split($text))). The built-in string reverse function strrev breaks multi-byte UTF-8 characters.

How to reverse a string in Java?

For a reverse string in Java, use new StringBuilder(text).reverse().toString(). StringBuilder keeps surrogate pairs together, but complex emoji sequences may still need grapheme-aware handling.

How to reverse a string without breaking emoji?

To reverse string without breaking emoji in JavaScript, split by graphemes with Intl.Segmenter, reverse the array and join it. Spreading the string with [...str] handles most emoji but not every combined sequence.

How to reverse word order in JavaScript?

Reverse word order in JavaScript with str.split(/\s+/).reverse().join(' '). To reverse words in a sentence while keeping punctuation attached, split on spaces only.