function queryToString obj if obj Object keys obj length return let Ob

function queryToString(obj) {
  if (!obj || !Object.keys(obj).length) return '';
  let q = '?';
  Object.keys(obj).forEach(key => q += `${encodeURIComponent(key)}=${encodeURIComponent(obj[key])}&`);
  q = q.replace(/\&$/, '');
  return q;
}