1. add
    1. #
  2. all
    1. >
    2. C
  3. alter
    1. >
    2. C
  4. any
    1. >
    2. C
  5. append
    1. S
  6. appendAll
    1. >
    2. A
  7. appendOne
    1. A
  8. assignDefaults
    1. >
    2. K
  9. assignOverrides
    1. >
    2. K
  10. compareByPath
  11. compareByProp
  12. compose
    1. >
  13. containedIn
    1. @
  14. contains
    1. >
    2. &
  15. dateIsBetween
    1. D
  16. defaultFalseyValTo
    1. @
  17. defaultNullishValTo
    1. @
  18. discard
    1. >
    2. C
  19. discardFirst
    1. >
    2. Q
  20. discardFirstWhile
    1. >
    2. A
  21. discardLast
    1. >
    2. Q
  22. discardLastWhile
    1. >
    2. A
  23. discardRange
    1. A
  24. discardWhen
    1. >
    2. C
  25. divideBy
    1. #
  26. endsWith
    1. S
  27. expand
    1. >
    2. S
  28. expandEnd
    1. >
    2. S
  29. expandStart
    1. >
    2. S
  30. fillRangeWith
    1. A
  31. fillWith
    1. A
  32. find
    1. C
  33. findKey
    1. E
  34. findKeyWithVal
    1. >
    2. $
  35. findLast
    1. A
  36. findLastKey
    1. >
    2. A
  37. findLastKeyWithVal
    1. >
    2. Q
  38. first
    1. >
    2. Q
  39. flattenFully
    1. A
  40. flattenOnce
    1. A
  41. flattenToDepth
    1. A
  42. forEach
    1. C
  43. get
    1. @
  44. getAtPath
    1. @
  45. getAverageValue
  46. getCommonValues
    1. >
  47. getExclusiveValues
  48. getKeys
    1. E
  49. getMaxValue
    1. C
  50. getMinValue
    1. C
  51. getRandomValue
    1. C
  52. getSize
    1. &
  53. getValueAtMapKey
    1. P
  54. getValues
    1. E
  55. greaterThan
    1. #
  56. greaterThanOrEqualTo
    1. #
  57. groupBy
    1. C
  58. invert
    1. K
  59. invokeWith
    1. F
  60. isAfter
    1. D
  61. isAtOrAfter
    1. D
  62. isAtOrBefore
    1. D
  63. isBefore
    1. D
  64. isEmpty
    1. &
  65. isFalsey
    1. @
  66. isLaden
    1. &
  67. isTruthy
    1. @
  68. joinValues
    1. C
  69. keep
    1. C
  70. keepFirst
    1. >
    2. Q
  71. keepFirstWhile
    1. >
    2. A
  72. keepLast
    1. >
    2. Q
  73. keepLastWhile
    1. >
    2. A
  74. keepRange
    1. Q
  75. keepWhen
    1. C
  76. last
    1. Q
  77. lessThan
    1. #
  78. lessThanOrEqualTo
    1. #
  79. mAppendAll
    1. M
    2. A
  80. mAppendOne
    1. M
    2. A
  81. mAssignDefaults
    1. M
    2. K
  82. mAssignOverrides
    1. M
    2. K
  83. mDiscardFirst
    1. >
    2. M
    3. A
  84. mDiscardFirstWhile
    1. >
    2. M
    3. A
  85. mDiscardLast
    1. >
    2. M
    3. A
  86. mDiscardLastWhile
    1. >
    2. M
    3. A
  87. mDiscardRange
    1. M
    2. A
  88. mFillRangeWith
    1. M
    2. A
  89. mFillWith
    1. M
    2. E
  90. mKeepFirst
    1. >
    2. M
    3. A
  91. mKeepFirstWhile
    1. >
    2. M
    3. A
  92. mKeepLast
    1. >
    2. M
    3. A
  93. mKeepLastWhile
    1. >
    2. M
    3. A
  94. mKeepRange
    1. M
    2. A
  95. mMapValues
    1. M
    2. E
  96. mOmit
    1. M
    2. E
  97. mOrder
    1. M
    2. A
  98. mPick
    1. M
    2. E
  99. mPrependAll
    1. M
    2. A
  100. mPrependOne
    1. M
    2. A
  101. mReverse
    1. M
    2. A
  102. mSet
    1. M
  103. mSetAtPath
    1. M
  104. mShuffle
    1. M
    2. A
  105. mUpdate
    1. M
    2. E
  106. mapKeys
    1. K
  107. mapValues
    1. C
  108. multiplyBy
    1. #
  109. negate
  110. numberIsBetween
    1. #
  111. omit
    1. E
  112. order
    1. A
  113. pAll
    1. >
    2. ǁ
    3. C
  114. pAny
    1. >
    2. ǁ
    3. C
  115. pCompose
    1. >
    2. ǁ
  116. pDiscardWhen
    1. >
    2. ǁ
    3. C
  117. pFind
    1. >
    2. ǁ
    3. C
  118. pForEach
    1. >
    2. ǁ
    3. C
  119. pKeepWhen
    1. >
    2. ǁ
    3. C
  120. pMapValues
    1. >
    2. ǁ
    3. C
  121. pPassThrough
    1. ǁ
  122. pResolveValues
    1. >
    2. ǁ
    3. C
  123. pWaitMs
    1. ǁ
  124. passThrough
  125. peek
    1. >
    2. @
  126. pick
    1. E
  127. prepend
    1. S
  128. prependAll
    1. >
    2. A
  129. prependOne
    1. A
  130. prune
    1. >
    2. S
  131. pruneEnd
    1. >
    2. S
  132. pruneStart
    1. >
    2. S
  133. randomlyKeep
    1. C
  134. replaceAllMatches
    1. >
    2. S
  135. replaceFirstMatch
    1. >
    2. S
  136. returnFirstArg
    1. >
    2. @
  137. returnUndefined
    1. >
  138. reverse
    1. A
  139. roundToNearest
    1. #
  140. set
    1. E
  141. shuffle
    1. A
  142. split
    1. S
  143. splitEvery
    1. >
    2. Q
  144. startsWith
    1. S
  145. strictEquals
    1. @
  146. subtract
    1. #
  147. sumValues
    1. C
  148. swapFirstTwoArgs
    1. F
  149. transpose
    1. >
  150. truncateToNChars
    1. S
  151. truncateToNLines
    1. S
  152. update
    1. E
  153. withDatesAscending
  154. withDatesDescending
  155. withNumbersAscending
  156. withNumbersDescending
  157. withStringsAscending
  158. withStringsDescending

findLastKey

findLastKey

  • (predicate: Predicate) => (anArray: array) => number | undefined

  1. Find the last index which passes a condition.

    Try It
    const lt3 = n => n < 3
const findLastKeyLt3 = findLastKey(lt3)

findLastKeyLt3([1, 2, 3]) // is 1
findLastKeyLt3([3, 4, 5]) // is undefined
const lt3 = (n: number) => n < 3
const findLastKeyLt3 = findLastKey(lt3)

findLastKeyLt3([1, 2, 3]) // is 1
findLastKeyLt3([3, 4, 5]) // is undefined
    Try It
    const lt3 = n => n < 3
const findLastKeyLt3 = findLastKey(lt3)

findLastKeyLt3([1, 2, 3]) // is 1
findLastKeyLt3([3, 4, 5]) // is undefined
const lt3 = (n: number) => n < 3
const findLastKeyLt3 = findLastKey(lt3)

findLastKeyLt3([1, 2, 3]) // is 1
findLastKeyLt3([3, 4, 5]) // is undefined

  2. Sometimes we want to find the last index that passes a condition. Below, we have Liz's schedule for the week. She can only take three appointments per day. Her client asks to schedule an appointment as late in the week as possible. Let's find which day she has open.

    Try It
    const dayOfWeek = ['monday', 'tuesday', 'wednesday', 'thursday', 'friday']

const appointmentsByDay = [
  ['9am-10', '11am-12', '1:30pm-3'],
  ['8:30am-10', '1pm-2', '2:30pm-3:30'],
  [],
  ['9:30am-10:30', '2pm-3'],
  ['8am-10', '11am-12', '1pm-3'],
]

const hasOpening = appts => appts.length < 3
const findLastOpening = findLastKey(hasOpening)
const lastOpeningIdx = findLastOpening(appointmentsByDay)
const lastOpeningDay = dayOfWeek[lastOpeningIdx]

console.log(lastOpeningDay)
// is thursday
const dayOfWeek = ['monday', 'tuesday', 'wednesday', 'thursday', 'friday']

const appointmentsByDay = [
  ['9am-10', '11am-12', '1:30pm-3'],
  ['8:30am-10', '1pm-2', '2:30pm-3:30'],
  [],
  ['9:30am-10:30', '2pm-3'],
  ['8am-10', '11am-12', '1pm-3'],
]

const hasOpening = (appts: string[]) => appts.length < 3
const findLastOpening = findLastKey(hasOpening)
const lastOpeningIdx = findLastOpening(appointmentsByDay)
const lastOpeningDay = dayOfWeek[lastOpeningIdx!]

console.log(lastOpeningDay)
// is thursday
    Try It
    const dayOfWeek = [
  'monday',
  'tuesday',
  'wednesday',
  'thursday',
  'friday',
]

const appointmentsByDay = [
  ['9am-10', '11am-12', '1:30pm-3'],
  ['8:30am-10', '1pm-2', '2:30pm-3:30'],
  [],
  ['9:30am-10:30', '2pm-3'],
  ['8am-10', '11am-12', '1pm-3'],
]

const hasOpening = appts => appts.length < 3
const findLastOpening = findLastKey(hasOpening)
const lastOpeningIdx = findLastOpening(
  appointmentsByDay
)
const lastOpeningDay = dayOfWeek[lastOpeningIdx]

console.log(lastOpeningDay)
// is thursday
const dayOfWeek = [
  'monday',
  'tuesday',
  'wednesday',
  'thursday',
  'friday',
]

const appointmentsByDay = [
  ['9am-10', '11am-12', '1:30pm-3'],
  ['8:30am-10', '1pm-2', '2:30pm-3:30'],
  [],
  ['9:30am-10:30', '2pm-3'],
  ['8am-10', '11am-12', '1pm-3'],
]

const hasOpening = (appts: string[]) =>
  appts.length < 3
const findLastOpening = findLastKey(hasOpening)
const lastOpeningIdx = findLastOpening(
  appointmentsByDay
)
const lastOpeningDay = dayOfWeek[lastOpeningIdx!]

console.log(lastOpeningDay)
// is thursday