JS在数组中返回,循环不休

const arr = [1, 2, 3, 4, 5];
const newArr = arr.map(item => item * 2);
console.log(newArr); // [2, 4, 6, 8, 10]

const arr = [1, 2, 3, 4, 5];
const newArr = arr.filter(item => item % 2 === 0);
console.log(newArr); // [2, 4]

const arr = [1, 2, 3, 4, 5];
const sum = arr.reduce((acc, item) => acc + item, 0);
console.log(sum); // 15

const arr = [1, 2, 3, 4, 5];
for (let i = 0; i < arr.length; i++) {
  if (arr[i] === 3) {
    break;
  }
  console.log(arr[i]);
}
// 输出：1 2

for (const item of arr) {
  if (item === 3) {
    break;
  }
  console.log(item);
}
// 输出：1 2