/**
 * 配列をn個ずつ抜き出す
 * 連想配列は処理できない
 */
class ArraySlice {
  /**
   * @param collection {array} - 配列
   * @param every {number} - n個(1以上の正数)
   */
  constructor (collection, every) {
    this._count = 0
    this._collection = collection
    this._every = every
  }

  /**
   * 配列の抜き出し
   * @return {T[]}
   */
  get () {
    const index = this._every * this._count
    this._count++
    return this._collection.slice(index, index + this._every)
  }

  /**
   * 次の抜き出す配列が存在するか
   * @return {boolean}
   */
  hasNext () {
    const index = this._every * this._count
    return this._collection.slice(index, index + this._every).length > 0
  }
}

const result = document.getElementById('result')
const collection = new ArraySlice([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 3)

document.getElementById('run').addEventListener('click', ()=>{
  let txt = []
  let count = 1
  
  while(collection.hasNext()){
    const res = collection.get()
    let arr = []
    let _txt = `${count}回目: [`
    
    for(let i = 0, iLen = res.length; i < iLen; i++){
      arr.push(res[i])
    }
    
    _txt += `${arr.join(', ')}]`
    txt.push(_txt)
    count++
  }
  
  result.innerHTML = txt.join('<br>')
})