Validation

ISO 3166-1 alpha-2 Country Code

Validate 2-letter ISO 3166-1 alpha-2 country codes (US, GB, FR, JP, etc.) — structural check only.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("^[A-Z]{2}$", "");
const input = "US";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

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

Python (re) code

pyPython

import re

pattern = re.compile(r"^[A-Z]{2}$")
input_text = "US"
for m in pattern.finditer(input_text):
    print(m.group(0))

Stdlib `re` module — no third-party dependency. Works on Python 3.6+.

Go (RE2) code

goGo

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`^[A-Z]{2}$`)
	input := `US`
	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

^[A-Z]{2}$

Raw source: ^[A-Z]{2}$

How it works

^[A-Z]{2}$ requires exactly two uppercase letters anchored to the full string. Like the currency-code pattern, this verifies FORMAT not membership — combine with the official list to ensure the code actually exists.