CFP - Docs - findLastKeyWithVal

findLastKeyWithVal

(value: any) => (sequence: Sequence) => number | undefined

Find the last index which has value.

Try It

const findLastKeyOfA = findLastKeyWithVal('a')

findLastKeyOfA(['a', 'b', 'a']) // is 2
findLastKeyOfA(['b', 'c']) // is undefined

findLastKeyOfA('aba') // is 2
const findLastKeyOfA = findLastKeyWithVal('a')

findLastKeyOfA(['a', 'b', 'a']) // is 2
findLastKeyOfA(['b', 'c']) // is undefined

findLastKeyOfA('aba') // is 2

Try It

const findLastKeyOfA = findLastKeyWithVal('a')

findLastKeyOfA(['a', 'b', 'a']) // is 2
findLastKeyOfA(['b', 'c']) // is undefined

findLastKeyOfA('aba') // is 2
const findLastKeyOfA = findLastKeyWithVal('a')

findLastKeyOfA(['a', 'b', 'a']) // is 2
findLastKeyOfA(['b', 'c']) // is undefined

findLastKeyOfA('aba') // is 2

Sometimes we want to find the last index to a value. Below, Chris starts a weightlifting program by seeing how many reps he can lift per level. Let's find the highest level where he can only lift one rep.

Try It

const repsPerWeightLevel = [12, 12, 10, 8, 6, 3, 1, 1, 0]

const findOneRepMax = findLastKeyWithVal(1)
const maxWeightLevel = findOneRepMax(repsPerWeightLevel)
console.log(maxWeightLevel)
// is 7
const repsPerWeightLevel = [12, 12, 10, 8, 6, 3, 1, 1, 0]

const findOneRepMax = findLastKeyWithVal(1)
const maxWeightLevel = findOneRepMax(repsPerWeightLevel)
console.log(maxWeightLevel)
// is 7

Try It

const repsPerWeightLevel = [
  12, 12, 10, 8, 6, 3, 1, 1, 0,
]

const findOneRepMax = findLastKeyWithVal(1)
const maxWeightLevel = findOneRepMax(
  repsPerWeightLevel
)
console.log(maxWeightLevel)
// is 7
const repsPerWeightLevel = [
  12, 12, 10, 8, 6, 3, 1, 1, 0,
]

const findOneRepMax = findLastKeyWithVal(1)
const maxWeightLevel = findOneRepMax(
  repsPerWeightLevel
)
console.log(maxWeightLevel)
// is 7