cssObjToCssString.js

const numberToPixel = prop => {
  if (!Number.isInteger(prop) || prop === 0) return prop;
  return `${prop}px`;
}

const camelToDash = str => str
  .replace(/(^[A-Z])/, ([first]) => first.toLowerCase())
  .replace(/([A-Z])/g, ([letter]) => `-${letter.toLowerCase()}`)


const cssObjectToString = (obj) => Object.entries(obj).reduce((styleString, entry) => (
  styleString + camelToDash(entry[0]) + ': ' + numberToPixel(entry[1]) + ';\n'
), '');