function dynamicallyLoadScript(url) {
    var script = document.createElement("script");  // create a script DOM node
    script.src = url;  // set its src to the provided URL
    document.head.appendChild(script);  // add it to the end of the head section of the page (could change 'head' to 'body' to add it to the end of the body section instead)
}

dynamicallyLoadScript('https://npmcdn.com/dexie/dist/dexie.js')

let database = new Dexie('database')

database.version(26)
  .stores({
    login: '',
    markets: null,
    groupsCatComp: '[category+competitionSlug], category, competitionSlug',
    groups: '[category+competitionSlug+nameSlug]',
    orders: 'id',
    statements: 'id',
    hotCompetitions: '++'
  })
  .upgrade((transaction) => {
    transaction.db.tables.forEach((table) => table.clear())
  })

database.open().catch(function(e) {
    console.error('Could not open database:', e)
})

async function quantity(db) {
  // count category by competition
  const result = {}
  await db.groupsCatComp
    .orderBy('[category+competitionSlug]')
    .each((item, cursor) => {
      result[cursor.primaryKey[0]] =
        // This works because ~~ will turn many non-number things into 0 after coercing to Number.
        ~~result[cursor.primaryKey[0]] + 1
      result[cursor.primaryKey[1]] = item.groups.size
    })
  console.log('quantity', result)  
}

quantity(database)