Simple Bem classname utility

bem.js

/**
 * Stupid simple BEM utility for class names. Useful for creating className strings in simple components
 * @param {string} block - Block name
 * @param {string} [element] - Element name
 * @param {string} [modifier] - modifier name
 * @return {string} A BEM string,
 * 
 * @example
 * bem('button', 'icon', 'red');
 * // returns 'button button--icon button--icon--red'
 * 
 * @example
 * bem('button', 'red');
 * // returns 'button button--red'
 */

function bem (block, element, modifier) { 
  const b = `${block}`;
  const e = element ? ` ${block}__${element}` : '';
  const m = modifier ?
    element ? ` ${block}__${element}--${modifier}` : ` ${block}--${modifier}`
    : '';
  return `${b}${e}${m}`
}