CFP - Docs - mDiscardFirstWhile

mDiscardFirstWhile

(predicate: Predicate) => (anArray: array) => anArray

Discard the first elements that pass a condition

Consider discardFirstWhile instead.
This is for the uncommon case where mutating anArray is required.

Try It

const lt3 = n => n < 3
const mDiscardFirstWhileLt3 = mDiscardFirstWhile(lt3)

const arr = [1, 2, 3, 4]
const mutatedArr = mDiscardFirstWhileLt3(arr)
console.log(mutatedArr === arr) // is true
console.log(arr) // is [3, 4]
const lt3 = (n: number) => n < 3
const mDiscardFirstWhileLt3 = mDiscardFirstWhile(lt3)

const arr = [1, 2, 3, 4]
const mutatedArr = mDiscardFirstWhileLt3(arr)
console.log(mutatedArr === arr) // is true
console.log(arr) // is [3, 4]

Try It

const lt3 = n => n < 3
const mDiscardFirstWhileLt3 =
  mDiscardFirstWhile(lt3)

const arr = [1, 2, 3, 4]
const mutatedArr = mDiscardFirstWhileLt3(arr)
console.log(mutatedArr === arr) // is true
console.log(arr) // is [3, 4]
const lt3 = (n: number) => n < 3
const mDiscardFirstWhileLt3 =
  mDiscardFirstWhile(lt3)

const arr = [1, 2, 3, 4]
const mutatedArr = mDiscardFirstWhileLt3(arr)
console.log(mutatedArr === arr) // is true
console.log(arr) // is [3, 4]

This is useful when we have sorted data and don't need to filter over all of it. Below, we want to remove bots from our online game. We assign a "human score" to each character every night. With the sorted character list, let's remove those with a low score.

Try It

const characters = [
  { name: 'FireDragon', humanScore: 0 },
  { name: 'YouDontGnome', humanScore: 5 },
  { name: 'HeadlessNick', humanScore: 20 },
]

const isBot = ({ humanScore }) => humanScore < 10
const removeBots = mDiscardFirstWhile(isBot)
removeBots(characters)
console.log(characters)
// is [
//   { name: HeadlessNick, humanScore: 20 }
// ]
type Character = {
  name: string
  humanScore: number
}

const characters: Character[] = [
  { name: 'FireDragon', humanScore: 0 },
  { name: 'YouDontGnome', humanScore: 5 },
  { name: 'HeadlessNick', humanScore: 20 },
]

const isBot = ({ humanScore }: Character) => humanScore < 10
const removeBots = mDiscardFirstWhile(isBot)
removeBots(characters)
console.log(characters)
// is [
//   { name: HeadlessNick, humanScore: 20 }
// ]

Try It

const characters = [
  { name: 'FireDragon', humanScore: 0 },
  { name: 'YouDontGnome', humanScore: 5 },
  { name: 'HeadlessNick', humanScore: 20 },
]

const isBot = ({ humanScore }) => humanScore < 10
const removeBots = mDiscardFirstWhile(isBot)
removeBots(characters)
console.log(characters)
// is [
//   { name: HeadlessNick, humanScore: 20 }
// ]
type Character = {
  name: string
  humanScore: number
}

const characters: Character[] = [
  { name: 'FireDragon', humanScore: 0 },
  { name: 'YouDontGnome', humanScore: 5 },
  { name: 'HeadlessNick', humanScore: 20 },
]

const isBot = ({ humanScore }: Character) =>
  humanScore < 10
const removeBots = mDiscardFirstWhile(isBot)
removeBots(characters)
console.log(characters)
// is [
//   { name: HeadlessNick, humanScore: 20 }
// ]