switch (true) {
  case /[A-Z]{3}-\w\d+/g.test(str):
  case /[A-Z]{1,3}\d+/g.test(str):
  case /\s\d+/g.test(str):
    return true;
  default:
    return false;
}

import React, { useState } from 'react';
import './selectserver.scss';
import ShareIcon from '@material-ui/icons/Share';
import KeyboardArrowDownIcon from '@material-ui/icons/KeyboardArrowDown';

const SomeComponent = () => {
  const [select, setSelect] = useState(false);

  const toggleServer = () => setSelect(!select);

  return (
    <>
      <div className="login__select__block">
        <ShareIcon className="login__select__img" />
        <div onClick={toggleServer} className="login__select__input">
          Выберете сервер
        </div>
        <KeyboardArrowDownIcon className="login__select__arrow" />
      </div>
      {select && (
        <div className="login__select__under">
          <div className="login__select__elem">Smile</div>
          <div className="login__select__elem">Smile</div>
          <div className="login__select__elem">Smile</div>
        </div>
      )}
    </>
  );
};

export default SomeComponent;