Validation

Alphanumeric Only

Match strings containing only letters (A–Z, a–z) and digits (0–9), with no spaces or special characters.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("^[a-zA-Z0-9]+$", "");
const input = "Hello123";
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-zA-Z0-9]+$")
input_text = "Hello123"
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-zA-Z0-9]+$`)
	input := `Hello123`
	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-zA-Z0-9]+$

Raw source: ^[a-zA-Z0-9]+$

How it works

^ and $ anchor to the full string. [a-zA-Z0-9]+ requires one or more characters from the combined letter and digit set. Any space, punctuation, or symbol will cause the match to fail.