A code sample from the article https://www.joshwulf.com/blog/2020/02/avoid-global-state/

using-validation-helpers.js

const GlobalMemberStore = (() => {
  let _members = []
  const Store = {
    putMember: member => {
      // Validate required args
      const m = needsId(needsArg(member))
      if (Store.getMember(m.id).found) {
        throw new Error(`${m.id} already exists!`)
      }
      _members = [..._members, {...m}]
    }
  }
  return Store
})()