debounce incoming requests ensuring max X requests are handled at the same time and debouncing gradually in batches

debounce.js

const debounce = (
  fn,
  { debounceInterval = 50, maxConcurrentRequests = 15, unstackCount = 10 } = {},
) => {
  let queue = []
  let pendingCount = 0
  const debouncedFn = async (request) => {
    let entry
    const promise = new Promise((resolve, reject) => {
      entry = { request, resolve, reject }
    })

    if (pendingCount < maxConcurrentRequests) {
      perform(entry)
      return promise
    }
    queue.push(entry)
    return promise
  }

  const perform = async ({ request, resolve, reject }) => {
    try {
      const value = await fn(request)
      pendingCount--
      resolve(value)
    } catch (e) {
      pendingCount--
      reject(e)
    }
  }

  const tick = () => {
    const todo = queue.slice(0, unstackCount)
    queue = queue.slice(unstackCount)
    todo.forEach(perform)
  }

  const interval = setInterval(tick, debounceInterval)

  debouncedFn.cancel = () => {
    clearInterval(interval)
  }
  return debouncedFn
}