7 methods to query between dates in MongoDB using the greater than ($gte) operator and the less than ($lt) operator

mongodb-query-dates.js

  let docs

  // METHOD 1 - new Date() +1 day
  const startDate = new Date('2021-03-31 00:00')
  const endDate = new Date(startDate.getTime() + 86400000)
  docs = await collection.find({
    date1: {
      $gte: startDate,
      $lt: endDate
    }
  }).toArray()
  console.log('method 1', docs.length)

  // METHOD 2 - dayjs: startOf/endOf
  docs = await collection.find({
    date1: {
      $gte: dayjs('2021-03-31').startOf('day').toDate(),
      $lt: dayjs('2021-03-31').endOf('day').toDate()
      }
  }).toArray()
  console.log('method 2', docs.length)

  // METHOD 3 - timestamp
  docs = await collection.find({
    date1: {
      $gte: new Date(dayjs('2021-03-31 00:00').unix() * 1000),
      $lt: new Date(dayjs('2021-03-31 23:59').unix() * 1000)
     }
  }).toArray()
  console.log('method 3', docs.length)

  // METHOD 4 - dayjs: Exact time
  docs = await collection.find({
    date1: {
      $gte: dayjs('2021-03-31 00:00').toDate(),
      $lt: dayjs('2021-03-31 23:59').toDate()
     }
  }).toArray()
  console.log('method 4', docs.length)

  // METHOD 5 - new Date() extact time
  const startDate2 = new Date('2021-03-31 00:00')
  const endDate2 = new Date('2021-03-31 23:59')
  docs = await collection.find({
    date1: {
      $gte: startDate2,
      $lt: endDate2
    }
  }).toArray()
  console.log('method 5', docs.length)

  // METHOD 6 - dayjs: add +1 day
  docs = await collection.find({
    date1: {
      $gte: dayjs('2021-03-31').toDate(),
      $lt: dayjs('2021-03-31').add(1, 'day').toDate()
    }
  }).toArray()
  console.log('method 6', docs.length)

  function getDateRange (dt1, dt2=dt1) {
    const startDate = new Date(dt1 + ' 00:00')
    const endDate = new Date(new Date(dt2 + ' 00:00').getTime() + 86400000)
    return {
      $gte: startDate,
      $lt: endDate
    }
  }

  // METHOD 7 - custom function with new Date()
  docs = await collection.find({
    date1: getDateRange('2021-03-31')
  }).toArray()
  console.log('method 7', docs.length)

  console.log(dayjs('2021-03-31 00:00').toISOString())
  console.log(new Date('2021-03-31 00:00').toISOString())
  console.log(new Date('2021-03-31').toISOString()) // There is a difference here