2021-05-05 10:13:49 -07:00
|
|
|
|
---
|
|
|
|
|
id: 56592a60ddddeae28f7aa8e1
|
|
|
|
|
title: 使用索引訪問多維數組
|
|
|
|
|
challengeType: 1
|
|
|
|
|
videoUrl: 'https://scrimba.com/c/ckND4Cq'
|
|
|
|
|
forumTopicId: 16159
|
|
|
|
|
dashedName: access-multi-dimensional-arrays-with-indexes
|
|
|
|
|
---
|
|
|
|
|
|
|
|
|
|
# --description--
|
|
|
|
|
|
|
|
|
|
我們可以把<dfn>多維</dfn>數組看作成是*數組中的數組*。 使用方括號表示法訪問數組時,第一個方括號訪問的是數組的最外層(第一層),第二個方括號訪問的是數組的第二層,以此類推。
|
|
|
|
|
|
|
|
|
|
**例如:**
|
|
|
|
|
|
|
|
|
|
```js
|
2021-10-27 15:10:57 +00:00
|
|
|
|
const arr = [
|
|
|
|
|
[1, 2, 3],
|
|
|
|
|
[4, 5, 6],
|
|
|
|
|
[7, 8, 9],
|
|
|
|
|
[[10, 11, 12], 13, 14]
|
2021-05-05 10:13:49 -07:00
|
|
|
|
];
|
2021-10-27 15:10:57 +00:00
|
|
|
|
|
2021-05-05 10:13:49 -07:00
|
|
|
|
arr[3];
|
|
|
|
|
arr[3][0];
|
|
|
|
|
arr[3][0][1];
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
`arr[3]` 爲 `[[10, 11, 12], 13, 14]`,`arr[3][0]` 爲 `[10, 11, 12]`,並且 `arr[3][0][1]` 爲 `11`。
|
|
|
|
|
|
2021-05-10 01:12:02 +05:30
|
|
|
|
**注意:** 數組名與方括號之間不應該有任何空格,比如 `array [0][0]` 甚至是 `array [0] [0]` 都是不允許的。 儘管 JavaScript 能夠正確處理這種情況,但是當其他程序員閱讀你寫的代碼時,這可能讓他們感到困惑。
|
2021-05-05 10:13:49 -07:00
|
|
|
|
|
|
|
|
|
# --instructions--
|
|
|
|
|
|
|
|
|
|
使用方括號從 `myArray` 中選取一個值,使得 `myData` 等於 `8`。
|
|
|
|
|
|
|
|
|
|
# --hints--
|
|
|
|
|
|
|
|
|
|
`myData` 應該等於 `8`。
|
|
|
|
|
|
|
|
|
|
```js
|
|
|
|
|
assert(myData === 8);
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
你應該使用方括號從 `myArray` 中讀取正確的值。
|
|
|
|
|
|
|
|
|
|
```js
|
|
|
|
|
assert(/myData=myArray\[2\]\[1\]/.test(__helpers.removeWhiteSpace(code)));
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
# --seed--
|
|
|
|
|
|
|
|
|
|
## --after-user-code--
|
|
|
|
|
|
|
|
|
|
```js
|
|
|
|
|
if(typeof myArray !== "undefined"){(function(){return "myData: " + myData + " myArray: " + JSON.stringify(myArray);})();}
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
## --seed-contents--
|
|
|
|
|
|
|
|
|
|
```js
|
2021-10-27 15:10:57 +00:00
|
|
|
|
const myArray = [
|
|
|
|
|
[1, 2, 3],
|
|
|
|
|
[4, 5, 6],
|
|
|
|
|
[7, 8, 9],
|
|
|
|
|
[[10, 11, 12], 13, 14],
|
|
|
|
|
];
|
2021-05-05 10:13:49 -07:00
|
|
|
|
|
2021-10-27 15:10:57 +00:00
|
|
|
|
const myData = myArray[0][0];
|
2021-05-05 10:13:49 -07:00
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
# --solutions--
|
|
|
|
|
|
|
|
|
|
```js
|
2021-10-27 15:10:57 +00:00
|
|
|
|
const myArray = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [[10, 11, 12], 13, 14]];
|
|
|
|
|
const myData = myArray[2][1];
|
2021-05-05 10:13:49 -07:00
|
|
|
|
```
|