const queue = []
Object.defineProperty(queue, 'push', {
  configurable: true,
  enumerable: false,
  writable: true,
  value: function (...args) {
    console.log('queue changed')
    if (typeof args[0] === 'function') args[0]()
    return Array.prototype.push.apply(this, args)
  }
})
  
const data = []

async function getData() {
  return data
}

async function setData(v, d) {
  console.log((v === (data[Object.values(data).length - 1] || 0) + 1 ? 'in' : 'out of') + ' sync')
  data.push(v)
}

function someEventTrigger(evtId) {
  queue.push(async () => {
    let data = await getData()
    await setData(evtId, data)
  })

  // is async, happens so fast would be empty
  console.log('data:', data)
}

// trigger lots of things
for (let i = 0; i < 10; i++) someEventTrigger(i)
 
// trigger on thing
document.write('<button onclick="someEventTrigger((data[Object.values(data).length - 1] || 0) + 1)">Trigger</button>')