pico-cookie.js

const cookie = (() => {
  const encode = encodeURIComponent
  const decode = decodeURIComponent
  return Object.defineProperty(
    new Proxy(
      Object.fromEntries(
        document.cookie.split(';').map(
          entry => entry.split('=').map(e => decode(e.trim()))
        )
      ),
      {
        set(_, key, value) {
          document.cookie = `${ encode(key) }=${ encode(value) }`
          return Reflect.set(...arguments)
        },
        deleteProperty(_, key) {
          document.cookie = `${ encode(key) }=; max-age=0`
          return Reflect.deleteProperty(...arguments)
        }
      }
    ),
    'put',
    {
      value(key, value, attributes) {
        document.cookie = `${ encode(key) }=${ encode(value) }` + (
          attributes ? '; ' + Object.entries(attributes).map(
            pair => pair.map(p => encode(p)).join('=')
          ).join('; ') : ''
        )
        this[key] = value
        return this
      }
    }
  )
})()