utils.js

const _setCorsHeaders = res => {
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.setHeader('Access-Control-Allow-Headers', '*');
    res.setHeader('Access-Control-Allow-Methods', '*');
    return res;
};
function getExt(fileName) {
  const match = fileName.match(/\.([^\.]+)$/);
  return match && match[1].toLowerCase();
}
const makePromise = () => {
  let accept, reject;
  const p = new Promise((a, r) => {
    accept = a;
    reject = r;
  });
  p.accept = accept;
  p.reject = reject;
  return p;
};

function parseQuery(queryString) {
  const query = {};
  const pairs = (queryString[0] === '?' ? queryString.substr(1) : queryString).split('&');
  for (let i = 0; i < pairs.length; i++) {
    const pair = pairs[i].split('=');
    const k = decodeURIComponent(pair[0]);
    if (k) {
      const v = decodeURIComponent(pair[1] || '');
      query[k] = v;
    }
  }
  return query;
}

module.exports = {
  _setCorsHeaders,
  getExt,
  makePromise,
  parseQuery
}