CFP - Docs - keepLast

keepLast

(num: number) => (sequence: Sequence) => Sequence

Keep the last num elements of a sequence

Try It

const keepLastThree = keepLast(3)

keepLastThree(['a', 'b', 'c', 'd']) // is ['b', 'c', 'd']
keepLastThree('abcd') // is 'bcd'
keepLastThree(['a']) // is ['a']
const keepLastThree = keepLast(3)

keepLastThree(['a', 'b', 'c', 'd']) // is ['b', 'c', 'd']
keepLastThree('abcd') // is 'bcd'
keepLastThree(['a']) // is ['a']

Try It

const keepLastThree = keepLast(3)

keepLastThree(['a', 'b', 'c', 'd']) // is ['b', 'c', 'd']
keepLastThree('abcd') // is 'bcd'
keepLastThree(['a']) // is ['a']
const keepLastThree = keepLast(3)

keepLastThree(['a', 'b', 'c', 'd']) // is ['b', 'c', 'd']
keepLastThree('abcd') // is 'bcd'
keepLastThree(['a']) // is ['a']

Sometimes we have ordered data and only care about the last elements. Below, we have a list of soccer teams ordered by league placement. The last three teams have to move to the lower league. Let's list them.

Try It

const teamsByPlacement = [
  'Manchester United',
  'Tottenham Hotspur',
  'West Ham United',
  'Ipswich Town',
  'Leicester City',
  'Southampton',
]

const getRelegatedTeams = keepLast(3)
const relegatedTeams = getRelegatedTeams(teamsByPlacement)
console.log(relegatedTeams)
// is [
//   Ipswich Town
//   Leicester City
//   Southampton
// ]
const teamsByPlacement = [
  'Manchester United',
  'Tottenham Hotspur',
  'West Ham United',
  'Ipswich Town',
  'Leicester City',
  'Southampton',
]

const getRelegatedTeams = keepLast(3)
const relegatedTeams = getRelegatedTeams(teamsByPlacement)
console.log(relegatedTeams)
// is [
//   Ipswich Town
//   Leicester City
//   Southampton
// ]

Try It

const teamsByPlacement = [
  'Manchester United',
  'Tottenham Hotspur',
  'West Ham United',
  'Ipswich Town',
  'Leicester City',
  'Southampton',
]

const getRelegatedTeams = keepLast(3)
const relegatedTeams = getRelegatedTeams(
  teamsByPlacement
)
console.log(relegatedTeams)
// is [
//   Ipswich Town
//   Leicester City
//   Southampton
// ]
const teamsByPlacement = [
  'Manchester United',
  'Tottenham Hotspur',
  'West Ham United',
  'Ipswich Town',
  'Leicester City',
  'Southampton',
]

const getRelegatedTeams = keepLast(3)
const relegatedTeams = getRelegatedTeams(
  teamsByPlacement
)
console.log(relegatedTeams)
// is [
//   Ipswich Town
//   Leicester City
//   Southampton
// ]