Webflags: u

Slug (Unicode Letters Allowed)

Validate URL slugs allowing Unicode letters (`café-rénové`), as supported by Next.js i18n routing.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("^[\\p{L}\\p{N}]+(?:-[\\p{L}\\p{N}]+)*$", "u");
const input = "hello-world";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).

Why it doesn't work in PY

CPython's stdlib `re` doesn't support `\p{...}` Unicode property escapes (those need the third-party `regex` package).

Approach

Replace `\p{L}` with explicit Unicode ranges, or drop the `u` flag if you only need ASCII matching.

Read the full guide →

Workaround code in Python (re)

pyPython (workaround)

# Option A: install the third-party `regex` package which DOES
# support \p{...} property escapes (drop-in replacement for `re`).
#
#   pip install regex
import regex
pattern = regex.compile(r'^[\p{L}\p{N}]+(?:-[\p{L}\p{N}]+)*$', regex.UNICODE)
matches = pattern.findall("café-rénové hello-world")
print(matches)


# Option B: stay on stdlib `re` and use explicit Unicode ranges for
# the categories you need. Below covers Latin letters + Latin-1 +
# Latin-Extended (handles café, naïve, résumé, etc.).
import re
pattern = re.compile(
    r'[A-Za-z\u00C0-\u024F\u1E00-\u1EFF]+',
    re.UNICODE,
)
matches = pattern.findall("café-rénové hello-world")
print(matches)

Two paths: install the `regex` package (full \p{} support) or stay on stdlib `re` with explicit Unicode block ranges.

Go (RE2) code

goGo

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`^[\p{L}\p{N}]+(?:-[\p{L}\p{N}]+)*$`)
	input := `hello-world`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}

Uses `regexp.MustCompile` (panics on bad patterns at startup) and `FindAllString` for all matches.

Pattern

regexengine-agnostic

^[\p{L}\p{N}]+(?:-[\p{L}\p{N}]+)*$   (flags: u)

Raw source: ^[\p{L}\p{N}]+(?:-[\p{L}\p{N}]+)*$

How it works

[\p{L}\p{N}]+ matches one or more Unicode letters or numbers (so `café` and `東京` are valid). (?:-[\p{L}\p{N}]+)* allows additional hyphen-separated segments. The u flag is REQUIRED in JavaScript for \p{} property escapes; Python's stdlib `re` doesn't support \p{} (use \w with Unicode flag, or the `regex` package); Go RE2 has its own \p{...} support.