components/grid/row.js
function getModifierClassNames(props) {
  return modifierKeys.reduce((result, key) => {
    if (props[key]) {
      return result.concat(styles[`${key}-${props[key]}`]);
    }
    return result;
  }, []);
}
function getModifierClassNames(props) {
  return modifierKeys.reduce((result, key) => {
    if (props[key]) {
      return result.concat(styles[`${key}-${props[key]}`]);
    }
    return result;
  }, []);
}
function getModifierClassNames ( props ) { return modifierKeys . reduce ( ( result , key ) => { if ( props [ key ] ) { return result . concat ( styles [ ` ${ key } ${ props [ key ] } ` ] ) ; } return result ; } , [ ] ) ; }
Converts xs="middle" to class "middle-xs"
@param {Object} props incoming props
@returns {Array} result modifier classes
Converts xs = middle to class middle - xs