Just three simple functions to wrap browser's cookie API

cookie.js

function setCookie(name, value, days=0, hours=0, minutes=0) {
  if (!days && !hours && !minutes) days = 1
  const milliseconds = ((days*24+hours)*60+minutes)*60*1000,
        expire = new Date(Date.now()+milliseconds)
  document.cookie =
    name+'='+value+'; path=/; expires='+expire.toUTCString()
  return value
}

function getCookie(name) {
  const matches = document.cookie.match(new RegExp('(?:^|; )'+
    name.replace(/([\.$?*|{}\(\)\[\]\\\/\+^])/g,'\\$1')+'=([^;]*)'));
  return matches? decodeURIComponent(matches[1]) : undefined;
}

delCookie = name=> name? setCookie(name,'',-1) :
  document.cookie.split(";").forEach(c=> document.cookie = c.replace(/^ +/,'')
    .replace(/=.*/,"=;expires="+ new Date().toUTCString() +";path=/"))