Regex for CSS ID Selector

javascript

const regex = /^#[_a-zA-Z][_a-zA-Z0-9-]*$/;
const isValid = regex.test(value);

python

import re
pattern = r'^#[_a-zA-Z][_a-zA-Z0-9-]*$'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /^#[_a-zA-Z][_a-zA-Z0-9-]*$/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/^#[_a-zA-Z][_a-zA-Z0-9-]*$/', $value)) {
    echo "valid";
}

java

String pattern = "^#[_a-zA-Z][_a-zA-Z0-9-]*$";
boolean isValid = value.matches(pattern);