divide array

slice-array.js

const a = [1,2,3,4,5,6,7,8]
const newarr=[]
const cols = 4
const interactions = a.length/cols

let index = 0

console.log(interactions)

for (let i = 0; i < interactions;i++) {
  const slice = a.slice(index, index + cols)
  newarr.push(slice)
  index += cols
}

newarr // [ [ 1, 2, 3, 4 ], [ 5, 6, 7, 8 ] ]