JS 配列の指定の範囲を別の要素に置き換える

lodashのfillメゾッドを作ってみた

▶︎lodath fill

const fill = (array = [], value, start = 0, end = array.length) => {
  const fillArray = []
  for (let i = 0; i < array.length; i++) {
    if (start <= i && i < end) {
      fillArray.push(value)
    } else {
      fillArray.push(array[i])
    }
  }
  return fillArray
}

console.log(fill([1, 2, 3], "a"))
// => [ 'a', 'a', 'a' ]

console.log(fill(Array(3), 2))
// => [ 2, 2, 2 ]

console.log(fill([4, 6, 8, 10], "*", 1, 3))
// => [ 4, '*', '*', 10 ]

もう少し省略できた

const fill = (array = [], value, start = 0, end = array.length) => {
  for (let i = 0; i < array.length; i++) {
    if (start <= i && i < end) {
      array[i] = value
    } 
  return array
}