BEM naming convention helper for React Components

bemHelper.js

// Helper function to generate String of class names for a block in BEM naming
// convention. Enter a block name (string) and modifiers (array) to return a 
// string with block name class and all modifier classes.
export default function bemHelper(block, modifiers) {
  if (modifiers) {
    const classesArray = modifiers.map(modifier => `${block}--${modifier}`);
    const classes = classesArray.join(' ');
    return `${block} ${classes}`;
  } else {
    return block;
  }
}