rambdax/src/intersperse.js

Extended version of Rambda - a lightweight, faster alternative to Ramda

export function intersperse(separator, list){
  if (arguments.length === 1) return _list => intersperse(separator, _list)

  let index = -1
  const len = list.length
  const willReturn = []

  while (++index < len){
    if (index === len - 1){
      willReturn.push(list[ index ])
    } else {
      willReturn.push(list[ index ], separator)
    }
  }

  return willReturn
}