markdown 环

Posted 2021-05-05

## 陣列巡覽

```JavaScript
let iterable = [10, 20, 30]

for (let value of iterable) {
  value += 1
  console.log(value)
}
// 11
// 21
// 31
```

## 物件巡覽

```JavaScript
let iterable1 = new Map([['a', 1], ['b', 2], ['c', 3]])

for (const [key, value] of iterable1) {
  console.log(key + ':', value)
}

// a: 1
// b: 2
// c: 3
```

## 迭代尋覽

```JavaScript
function* fibonacci() {
  // a generator function
  let [prev, curr] = [0, 1]
  while (true) {
  ;[prev, curr] = [curr, prev + curr]
  yield curr
  }
}

for (let n of fibonacci()) {
  console.log(n)
  if (n >= 20) {
    break
  }
}
// 1
// 2
// 3
// 5
// 8
// 13
// 21
```