JavaScript 迴圈示範頁面

以下展示常用的 JavaScript 迴圈使用方式與輸出結果。

1. for 迴圈

for (let i = 0; i < 5; i++) {
  console.log(i);
}

2. while 迴圈

let i = 0;
while (i < 5) {
  console.log(i);
  i++;
}

3. do...while 迴圈

let i = 0;
do {
  console.log(i);
  i++;
} while (i < 5);

4. for...of 迴圈 (用於 array)

const fruits = ["apple", "banana", "orange"];
for (let f of fruits) {
  console.log(f);
}

5. for...in 迴圈 (用於 object)

const user = { name: "Tom", age: 20 };
for (let key in user) {
  console.log(key, user[key]);
}

6. break / continue

// break 範例
for (let i = 0; i < 10; i++) {
  if (i === 3) break;
  console.log(i);
}

// continue 範例
for (let i = 0; i < 5; i++) {
  if (i === 2) continue;
  console.log(i);
}