110 lines
2.0 KiB
Markdown
110 lines
2.0 KiB
Markdown
![]() |
---
|
|||
|
id: 5690307fddb111c6084545d7
|
|||
|
title: if else 語句中的邏輯順序
|
|||
|
challengeType: 1
|
|||
|
videoUrl: 'https://scrimba.com/c/cwNvMUV'
|
|||
|
forumTopicId: 18228
|
|||
|
dashedName: logical-order-in-if-else-statements
|
|||
|
---
|
|||
|
|
|||
|
# --description--
|
|||
|
|
|||
|
`if`、`else if` 語句中的代碼順序是很重要的。
|
|||
|
|
|||
|
在條件判斷語句中,代碼的執行順序是從上到下,所以你需要考慮清楚先執行哪一句,後執行哪一句。
|
|||
|
|
|||
|
這有兩個例子。
|
|||
|
|
|||
|
第一個例子:
|
|||
|
|
|||
|
```js
|
|||
|
function foo(x) {
|
|||
|
if (x < 1) {
|
|||
|
return "Less than one";
|
|||
|
} else if (x < 2) {
|
|||
|
return "Less than two";
|
|||
|
} else {
|
|||
|
return "Greater than or equal to two";
|
|||
|
}
|
|||
|
}
|
|||
|
```
|
|||
|
|
|||
|
第二個例子更改了代碼的執行順序:
|
|||
|
|
|||
|
```js
|
|||
|
function bar(x) {
|
|||
|
if (x < 2) {
|
|||
|
return "Less than two";
|
|||
|
} else if (x < 1) {
|
|||
|
return "Less than one";
|
|||
|
} else {
|
|||
|
return "Greater than or equal to two";
|
|||
|
}
|
|||
|
}
|
|||
|
```
|
|||
|
|
|||
|
這兩個函數看起來幾乎一模一樣,我們傳一個值進去看看它們有什麼區別。
|
|||
|
|
|||
|
```js
|
|||
|
foo(0)
|
|||
|
bar(0)
|
|||
|
```
|
|||
|
|
|||
|
`foo(0)` 將返回字符串 `Less than one`,`bar(0)` 將返回字符串 `Less than two`。
|
|||
|
|
|||
|
# --instructions--
|
|||
|
|
|||
|
更改函數的邏輯順序以便通過所有的測試用例。
|
|||
|
|
|||
|
# --hints--
|
|||
|
|
|||
|
`orderMyLogic(4)` 應該返回字符串 `Less than 5`
|
|||
|
|
|||
|
```js
|
|||
|
assert(orderMyLogic(4) === 'Less than 5');
|
|||
|
```
|
|||
|
|
|||
|
`orderMyLogic(6)` 應該返回字符串 `Less than 10`
|
|||
|
|
|||
|
```js
|
|||
|
assert(orderMyLogic(6) === 'Less than 10');
|
|||
|
```
|
|||
|
|
|||
|
`orderMyLogic(11)`應該返回 `Greater than or equal to 10`。
|
|||
|
|
|||
|
```js
|
|||
|
assert(orderMyLogic(11) === 'Greater than or equal to 10');
|
|||
|
```
|
|||
|
|
|||
|
# --seed--
|
|||
|
|
|||
|
## --seed-contents--
|
|||
|
|
|||
|
```js
|
|||
|
function orderMyLogic(val) {
|
|||
|
if (val < 10) {
|
|||
|
return "Less than 10";
|
|||
|
} else if (val < 5) {
|
|||
|
return "Less than 5";
|
|||
|
} else {
|
|||
|
return "Greater than or equal to 10";
|
|||
|
}
|
|||
|
}
|
|||
|
|
|||
|
orderMyLogic(7);
|
|||
|
```
|
|||
|
|
|||
|
# --solutions--
|
|||
|
|
|||
|
```js
|
|||
|
function orderMyLogic(val) {
|
|||
|
if(val < 5) {
|
|||
|
return "Less than 5";
|
|||
|
} else if (val < 10) {
|
|||
|
return "Less than 10";
|
|||
|
} else {
|
|||
|
return "Greater than or equal to 10";
|
|||
|
}
|
|||
|
}
|
|||
|
```
|