Email Domain Part (After @)

const re = new RegExp("^[a-zA-Z0-9](?:[a-zA-Z0-9.\\-]{0,253}[a-zA-Z0-9])?\\.[a-zA-Z]{2,24}$", "");
const input = "example.com";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

import re

pattern = re.compile(r"^[a-zA-Z0-9](?:[a-zA-Z0-9.\-]{0,253}[a-zA-Z0-9])?\.[a-zA-Z]{2,24}$")
input_text = "example.com"
for m in pattern.finditer(input_text):
    print(m.group(0))

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`^[a-zA-Z0-9](?:[a-zA-Z0-9.\-]{0,253}[a-zA-Z0-9])?\.[a-zA-Z]{2,24}$`)
	input := `example.com`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}