js의 배열에서 요소의 발생 찾기

코드 -

let array = [6,1,4,4,2,8,3,4,4,4,5,10,5,9,11,
6,1,4,4,2,8,3,4,4,4,5,10,5,9,11,6,1,4,4,2,8,3,4,4,4,5,10,5,9,11];
let target = 4

const occurences = (array,target) => {
  let result = 0
  let index = []
  for (let i = 1; i <= array.length + 1; i++) {
    if(array[i] === target){
     result++
     index.push(i)
    }
    else{
      continue
    }
  }
  return `${target} occured ${result.length} times at indexes - ${index}`
}

console.log(occurences(array,target))

출력 -

4 occured 15 times at indexes - 2,3,7,8,9,17,18,22,23,24,32,33,37,38,39