CFP - Docs - findLast

findLast

(predicate: Predicate) => (anArray: array) => Value | undefined

Find the last value which passes a condition.

Try It

const lt3 = n => n < 3
const findLastLt3 = findLast(lt3)

findLastLt3([1, 2, 3]) // is 2
findLastLt3([3, 4, 5]) // is undefined
const lt3 = (n: number) => n < 3
const findLastLt3 = findLast(lt3)

findLastLt3([1, 2, 3]) // is 2
findLastLt3([3, 4, 5]) // is undefined

Try It

const lt3 = n => n < 3
const findLastLt3 = findLast(lt3)

findLastLt3([1, 2, 3]) // is 2
findLastLt3([3, 4, 5]) // is undefined
const lt3 = (n: number) => n < 3
const findLastLt3 = findLast(lt3)

findLastLt3([1, 2, 3]) // is 2
findLastLt3([3, 4, 5]) // is undefined

Sometimes we want to find the last value that passes a condition. Below, we have some of Jim Carrey's oldest films ordered by release date. Let's find his oldest film, which wasn't a comedy.

Try It

const movies = getMovies()

const isNotComedy = movie => !movie.categories.includes('comedy')
const findOldestNonComedy = findLast(isNotComedy)
const oldestNonComedy = findOldestNonComedy(movies)

console.log(oldestNonComedy.title)
// is "Mike Hammer: Murder Takes All"

function getMovies() {
  return [
    {
      title: 'Doing Time on Maple Drive',
      categories: ['drama'],
      released: 1992,
    },
    {
      title: 'Mike Hammer: Murder Takes All',
      categories: ['crime', 'mystery', 'thriller'],
      released: 1989,
    },
    {
      title: 'Copper Mountain',
      categories: ['comedy'],
      released: 1983,
    },
    {
      title: 'All In Good Taste',
      categories: ['comedy'],
      released: 1983,
    },
    {
      title: 'Rubberface',
      categories: ['comedy', 'drama'],
      released: 1981,
    },
  ]
}
type Movie = {
  title: string
  categories: string[]
  released: number
}

const movies = getMovies()

const isNotComedy = (movie: Movie) => !movie.categories.includes('comedy')
const findOldestNonComedy = findLast(isNotComedy)
const oldestNonComedy = findOldestNonComedy(movies)

console.log(oldestNonComedy?.title)
// is "Mike Hammer: Murder Takes All"

function getMovies(): Movie[] {
  return [
    {
      title: 'Doing Time on Maple Drive',
      categories: ['drama'],
      released: 1992,
    },
    {
      title: 'Mike Hammer: Murder Takes All',
      categories: ['crime', 'mystery', 'thriller'],
      released: 1989,
    },
    {
      title: 'Copper Mountain',
      categories: ['comedy'],
      released: 1983,
    },
    {
      title: 'All In Good Taste',
      categories: ['comedy'],
      released: 1983,
    },
    {
      title: 'Rubberface',
      categories: ['comedy', 'drama'],
      released: 1981,
    },
  ]
}

Try It

const movies = getMovies()

const isNotComedy = movie =>
  !movie.categories.includes('comedy')
const findOldestNonComedy = findLast(isNotComedy)
const oldestNonComedy =
  findOldestNonComedy(movies)

console.log(oldestNonComedy.title)
// is "Mike Hammer: Murder Takes All"

function getMovies() {
  return [
    {
      title: 'Doing Time on Maple Drive',
      categories: ['drama'],
      released: 1992,
    },
    {
      title: 'Mike Hammer: Murder Takes All',
      categories: [
        'crime',
        'mystery',
        'thriller',
      ],
      released: 1989,
    },
    {
      title: 'Copper Mountain',
      categories: ['comedy'],
      released: 1983,
    },
    {
      title: 'All In Good Taste',
      categories: ['comedy'],
      released: 1983,
    },
    {
      title: 'Rubberface',
      categories: ['comedy', 'drama'],
      released: 1981,
    },
  ]
}
type Movie = {
  title: string
  categories: string[]
  released: number
}

const movies = getMovies()

const isNotComedy = (movie: Movie) =>
  !movie.categories.includes('comedy')
const findOldestNonComedy = findLast(isNotComedy)
const oldestNonComedy =
  findOldestNonComedy(movies)

console.log(oldestNonComedy?.title)
// is "Mike Hammer: Murder Takes All"

function getMovies(): Movie[] {
  return [
    {
      title: 'Doing Time on Maple Drive',
      categories: ['drama'],
      released: 1992,
    },
    {
      title: 'Mike Hammer: Murder Takes All',
      categories: [
        'crime',
        'mystery',
        'thriller',
      ],
      released: 1989,
    },
    {
      title: 'Copper Mountain',
      categories: ['comedy'],
      released: 1983,
    },
    {
      title: 'All In Good Taste',
      categories: ['comedy'],
      released: 1983,
    },
    {
      title: 'Rubberface',
      categories: ['comedy', 'drama'],
      released: 1981,
    },
  ]
}