batch.js

const noop = () => {}

function batch (reduce, options = {}) {
  const timeout = options.timeout || 1000
  const max = options.max || 10
  let calls = []
  let cancel = noop
  let flush = noop
  const reset = () => {
    clearTimeout(cancel)
    calls = []
    cancel = noop
    flush = noop
  }
  return Object.assign(
    (...args) => {
      calls.push(args)
      flush = () => {
        clearTimeout(cancel)
        reduce(calls)
        reset()
      }
      if (calls.length >= max) {
        flush()
        return;
      }
      clearTimeout(cancel)
      cancel = setTimeout(flush, timeout)
    },
    {
      cancel: reset,
      flush: () => flush()
    }
  )
}

// return () => calls.filter(c => c !== args)


const reducer = calls => console.log(calls.reduce((t, [f]) => t + f, ''))


const fn = batch(reducer, { timeout: 1000, max: 5 })

fn('M')
fn('i')
fn('k')
fn('e')
fn.flush()
fn('F')
fn('i')
fn('x')
fn.cancel()

//stdout: "Mike"