javascript implementation of https://www.rubydoc.info/stdlib/core/Enumerable:chunk_while

chunk_while.js

const chunk_while = (input, predicate) =>
  input.reduce((accumulator, current, index) => 
    index > 0 && predicate(input[index-1], current) &&
      [...accumulator.slice(0, accumulator.length-1), [...accumulator[accumulator.length-1], current]] ||
      [...accumulator, [current]]
  , [])

chunk_while.ts

const chunk_while = <T>(input: Array<T>, predicate: (elt_before: T, elt_after: T) => boolean) =>
  input.reduce((accumulator, current, index) => 
    index > 0 && predicate(input[index-1], current) &&
      [...accumulator.slice(0, accumulator.length-1), [...accumulator[accumulator.length-1], current]] ||
      [...accumulator, [current]]
  , [] as Array<Array<T>>)

chunk_while([1,2,1,2,2,1,1,2], x => x != 1) // => [[1], [2, 1], [2, 2, 1], [1], [2]]
chunk_while([1,2,4,9,10,11,12,15,16,19,20,21], (i, j) => i+1 == j) // => [[1, 2], [4], [9, 10, 11, 12], [15, 16], [19, 20, 21]]