CFP - Docs - isEmpty

isEmpty

(collection: Collection | string) => boolean

Test if a collection or string is empty

Try It

isEmpty([]) // is true
isEmpty([1]) // is false

isEmpty('') // is true
isEmpty('a') // is false
isEmpty([]) // is true
isEmpty([1]) // is false

isEmpty('') // is true
isEmpty('a') // is false

Try It

isEmpty([]) // is true
isEmpty([1]) // is false

isEmpty('') // is true
isEmpty('a') // is false
isEmpty([]) // is true
isEmpty([1]) // is false

isEmpty('') // is true
isEmpty('a') // is false

Usually we can iterate over collections without worrying whether they contain elements. Sometimes, however, we need to treat empty collections differently. Below, we have appointments scheduled for the next couple of days. Let's display "None" for the days without any appointments.

Try It

const appointments = {
  Monday: [],
  Tuesday: [
    {
      time: '8am-9:30',
      client: "Baz's Baby Furniture",
    },
    {
      time: '11am-12',
      client: 'University Of Florida',
    },
  ],
}

const displayOneAppt = ({ time, client }) => {
  return `  At: ${time}\n` + `  With: ${client}`
}

const displayDayAppts = (appts, day) => {
  if (isEmpty(appts)) return day + ': None'

  const dayAppts = appts.map(displayOneAppt).join('\n\n')
  return `${day}:\n` + dayAppts
}

const displayAllDayAppts = compose([
  mapValues(displayDayAppts),
  joinValues('\n\n'),
])

const apptDisplay = displayAllDayAppts(appointments)
console.log(apptDisplay)
// prints
// Monday: None
//
// Tuesday:
//   At: 8am-9:30
//   With: Baz's Baby Furniture
//
//   At: 11am-12
//   With: University Of Florida
type Appointment = {
  time: string
  client: string
}
type Appointments = Record<string, Appointment[]>
const appointments = {
  Monday: [],
  Tuesday: [
    {
      time: '8am-9:30',
      client: "Baz's Baby Furniture",
    },
    {
      time: '11am-12',
      client: 'University Of Florida',
    },
  ],
}

const displayOneAppt = ({ time, client }: Appointment) => {
  return `  At: ${time}\n` + `  With: ${client}`
}

const displayDayAppts = (appts: Appointment[], day: string) => {
  if (isEmpty(appts)) return day + ': None'

  const dayAppts = appts.map(displayOneAppt).join('\n\n')
  return `${day}:\n` + dayAppts
}

const displayAllDayAppts = compose([
  mapValues(displayDayAppts)<Appointments>,
  joinValues('\n\n'),
])

const apptDisplay = displayAllDayAppts(appointments)
console.log(apptDisplay)
// prints
// Monday: None
//
// Tuesday:
//   At: 8am-9:30
//   With: Baz's Baby Furniture
//
//   At: 11am-12
//   With: University Of Florida

Try It

const appointments = {
  Monday: [],
  Tuesday: [
    {
      time: '8am-9:30',
      client: "Baz's Baby Furniture",
    },
    {
      time: '11am-12',
      client: 'University Of Florida',
    },
  ],
}

const displayOneAppt = ({ time, client }) => {
  return `  At: ${time}\n` + `  With: ${client}`
}

const displayDayAppts = (appts, day) => {
  if (isEmpty(appts)) return day + ': None'

  const dayAppts = appts
    .map(displayOneAppt)
    .join('\n\n')
  return `${day}:\n` + dayAppts
}

const displayAllDayAppts = compose([
  mapValues(displayDayAppts),
  joinValues('\n\n'),
])

const apptDisplay =
  displayAllDayAppts(appointments)
console.log(apptDisplay)
// prints
// Monday: None
//
// Tuesday:
//   At: 8am-9:30
//   With: Baz's Baby Furniture
//
//   At: 11am-12
//   With: University Of Florida
type Appointment = {
  time: string
  client: string
}
type Appointments = Record<string, Appointment[]>
const appointments = {
  Monday: [],
  Tuesday: [
    {
      time: '8am-9:30',
      client: "Baz's Baby Furniture",
    },
    {
      time: '11am-12',
      client: 'University Of Florida',
    },
  ],
}

const displayOneAppt = ({
  time,
  client,
}: Appointment) => {
  return `  At: ${time}\n` + `  With: ${client}`
}

const displayDayAppts = (
  appts: Appointment[],
  day: string
) => {
  if (isEmpty(appts)) return day + ': None'

  const dayAppts = appts
    .map(displayOneAppt)
    .join('\n\n')
  return `${day}:\n` + dayAppts
}

const displayAllDayAppts = compose([
  mapValues(displayDayAppts)<Appointments>,
  joinValues('\n\n'),
])

const apptDisplay =
  displayAllDayAppts(appointments)
console.log(apptDisplay)
// prints
// Monday: None
//
// Tuesday:
//   At: 8am-9:30
//   With: Baz's Baby Furniture
//
//   At: 11am-12
//   With: University Of Florida