// take a number 6 -> binary

console.log(convert(10))

function convert(n){
  let remainder = []
  while (n){
    remainder.push(n % 2)
    n = parseInt(n/2) // keep dividing it
  }

  let l = remainder.length
  let ret = ''
  while (l--)
    ret +=remainder[l]
  return ret
  // or just do remainder.reverse().join('')
}