JavaScript:如何将数组forEach、映射、过滤器等转换为'for‘循环？

const arr = [1, 2, 3, 4, 5];

for (let i = 0; i < arr.length; i++) {
  console.log(arr[i]);
}

const arr = [1, 2, 3, 4, 5];
const mappedArr = [];

for (let i = 0; i < arr.length; i++) {
  mappedArr.push(arr[i] * 2);
}

console.log(mappedArr);

const arr = [1, 2, 3, 4, 5];
const filteredArr = [];

for (let i = 0; i < arr.length; i++) {
  if (arr[i] % 2 === 0) {
    filteredArr.push(arr[i]);
  }
}

console.log(filteredArr);