How to divide an array to chunks with flexible output length?

Question

How to divide an array to chunks with flexible output length?
it's necessary for render pagination, where we have limited place for elements,
and if we have several pages of elements — we need to display buttons with arrays (prev/next) instead el's.

example f() input-output, when 1st argument is Array with data,
and 2nd arg is maximum of elements in list, including nav-buttons:

      f([1,2,3,4], 4) => [1,2,3,4]
    f([1,2,3,4,5], 4) => [[1,2,3], [4,5]]
  f([1,2,3,4,5,6], 4) => [[1,2,3], [4,5,6]]
f([1,2,3,4,5,6,7], 4) => [[1,2,3], [4,5], [6,7]]
f([7,6,5,4,3,2,1], 4) => [[7,6,5], [4,3], [2,1]]
f([1,2,3,4,5,6,7], 6) => [[1,2,3,4,5], [6,7]]

Example of design-layout with max 6 elements

1st page:

2nd page:

Last page:

Answer 1

First, determine if one page/two pages are enough. If not, loop the array.

let f = (array, max) => {
  if (array.length / max <= 1)
    return array

  if (array.length / (max - 1) <= 2)
    return [array.slice(0, max - 1), array.slice(max - 1, array.length)]

  let result = []
  let n = 0
  while (n <= array.length - 1) {
    if (n == 0) {
      result.push(array.slice(n, n + max - 1))
      n += max - 1
    } else {
      let pushAmount = n+max-1 >= array.length ? max-1 : max-2
      result.push(array.slice(n, n + pushAmount))
      n += pushAmount
    }
  }

  return result
}

console.log(f([1, 2, 3, 4], 4))
console.log(f([1, 2, 3, 4, 5], 4))
console.log(f([1, 2, 3, 4, 5, 6], 4))
console.log(f([1, 2, 3, 4, 5, 6, 7], 4))
console.log(f([7, 6, 5, 4, 3, 2, 1], 4))
console.log(f([1, 2, 3, 4, 5, 6, 7], 6))