monthGaps.js

window['moment-range'].extendMoment(moment);

const storage = [
  ["2017-11", 0],
  ["2018-3", 1964105]
]

const storageGaps = function() {
  let gaps = []
	storage.map((current, index) => {
    if (storage.length > index + 1) {
      const currentMonth = storage[index]
    	const nextMonth = getNextMonth(index + 1, storage)
      gaps = gaps.concat(getRange(currentMonth, nextMonth))
    }
  })

  return gaps
}

const sayX = x => console.log('x is ' + x);

const getNextMonth = (index, months) => R.compose(
	R.head,
	R.nth(index),
  R.defaultTo([])
)(months)

const getRange = function(firstMonth, lastMonth) {
  const range = moment.range(R.head(firstMonth), lastMonth)
  const months = Array.from(range.by('month'))
  const yoyo = months.map(m => [
    m.format('YYYY-MM-DD'),
    firstMonth[1]
  ])
  
  return yoyo
}

console.log(storageGaps())