A wrapper around idb for creating multiple stores whenever

IdbWrapper.js

import { openDB } from 'idb'

export class IdbWrapper {
  static _freshStart = true
  static _checking = false
  static _dbCheck = null
  
  static _version = 1
  static _stores = new Set()

  // On page (re)loads we need to check _version,
  // this ensures we open with the correct version in getStore()
  // as a result db versions do start at 1 instead of 0
  _checkDbVersion (dbName) {
    IdbWrapper._checking = true

    return new Promise(resolve => {
      openDB(dbName).then(db => {
        IdbWrapper._stores = new Set(db.objectStoreNames)
        // version should be the number of stores +1
        IdbWrapper._version = db.objectStoreNames.length + 1
        
        db.close() // always close db
        IdbWrapper._freshStart = false
        IdbWrapper._checking = false
        resolve()
      })
    })
  }

  constructor (name, store) {
    this._name = name
    this._store = store

    if (IdbWrapper._freshStart && !IdbWrapper._checking) {
      IdbWrapper._dbCheck = this._checkDbVersion(this._name)
    }
  }

  // stores are created here instead of the constructor,
  // this way they're created only when needed
  async getStore (store = this._store) {
    await IdbWrapper._dbCheck

    if (IdbWrapper._stores.has(store)) return openDB(this._name)

    // I can't rely on db.objectStoreNames being up to date,
    // especially when making 2+ stores in a row
    IdbWrapper._stores.add(store)
    IdbWrapper._version = IdbWrapper._stores.size + 1

    return openDB(this._name, IdbWrapper._version, {
      upgrade: db => db.createObjectStore(store),
    })
  }

  // this function is for brevity since
  // we always get the store then close the db
  // it does mean we need to use strings for function names
  _autoclose (func, ...args) {
    return (async () => {
      const db = await this.getStore()
      const r = await db[func](...args)
      db.close() // always close db
      return r
    })()
  }

  saveValue (key, val) {
    return this._autoclose('put', this._store, val, key)
  }
  // other db functions as needed...
}