2018-10-10 22:03:03 +00:00
|
|
|
---
|
|
|
|
id: 56533eb9ac21ba0edf2244da
|
2021-03-15 03:20:39 +00:00
|
|
|
title: 介绍 else 语句
|
2018-10-10 22:03:03 +00:00
|
|
|
challengeType: 1
|
2020-04-29 10:29:13 +00:00
|
|
|
videoUrl: 'https://scrimba.com/c/cek4Efq'
|
|
|
|
forumTopicId: 18207
|
2021-01-13 02:31:00 +00:00
|
|
|
dashedName: introducing-else-statements
|
2018-10-10 22:03:03 +00:00
|
|
|
---
|
|
|
|
|
2020-12-16 07:37:30 +00:00
|
|
|
# --description--
|
|
|
|
|
2021-03-15 03:20:39 +00:00
|
|
|
当 `if` 语句的条件为真,会执行大括号里的代码。 那如果条件为假呢? 正常情况下什么也不会发生。 使用 `else` 语句,可以执行当条件为假时相应的代码。
|
2020-04-29 10:29:13 +00:00
|
|
|
|
|
|
|
```js
|
|
|
|
if (num > 10) {
|
|
|
|
return "Bigger than 10";
|
|
|
|
} else {
|
|
|
|
return "10 or Less";
|
|
|
|
}
|
|
|
|
```
|
|
|
|
|
2020-12-16 07:37:30 +00:00
|
|
|
# --instructions--
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2021-03-15 03:20:39 +00:00
|
|
|
请把多个 `if` 语句合并为一个 `if/else` 语句。
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2020-12-16 07:37:30 +00:00
|
|
|
# --hints--
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2021-03-15 03:20:39 +00:00
|
|
|
应该只有一个 `if` 语句。
|
2018-10-10 22:03:03 +00:00
|
|
|
|
|
|
|
```js
|
2020-12-16 07:37:30 +00:00
|
|
|
assert(code.match(/if/g).length === 1);
|
|
|
|
```
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2021-03-15 03:20:39 +00:00
|
|
|
应该使用一个 `else` 语句。
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2020-12-16 07:37:30 +00:00
|
|
|
```js
|
|
|
|
assert(/else/g.test(code));
|
|
|
|
```
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2021-03-15 03:20:39 +00:00
|
|
|
`testElse(4)` 应该返回字符串 `5 or Smaller`
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2020-12-16 07:37:30 +00:00
|
|
|
```js
|
|
|
|
assert(testElse(4) === '5 or Smaller');
|
2018-10-10 22:03:03 +00:00
|
|
|
```
|
|
|
|
|
2021-03-15 03:20:39 +00:00
|
|
|
`testElse(5)` 应该返回字符串 `5 or Smaller`
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2020-12-16 07:37:30 +00:00
|
|
|
```js
|
|
|
|
assert(testElse(5) === '5 or Smaller');
|
|
|
|
```
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2021-03-15 03:20:39 +00:00
|
|
|
`testElse(6)` 应该返回字符串 `Bigger than 5`
|
2020-12-16 07:37:30 +00:00
|
|
|
|
|
|
|
```js
|
|
|
|
assert(testElse(6) === 'Bigger than 5');
|
|
|
|
```
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2021-03-15 03:20:39 +00:00
|
|
|
`testElse(10)` 应该返回字符串 `Bigger than 5`
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2020-12-16 07:37:30 +00:00
|
|
|
```js
|
|
|
|
assert(testElse(10) === 'Bigger than 5');
|
|
|
|
```
|
2018-10-10 22:03:03 +00:00
|
|
|
|
2021-03-15 03:20:39 +00:00
|
|
|
不要修改相应注释的上面或下面的代码。
|
2020-04-29 10:29:13 +00:00
|
|
|
|
2018-10-10 22:03:03 +00:00
|
|
|
```js
|
2021-10-27 15:10:57 +00:00
|
|
|
assert(/let result = "";/.test(code) && /return result;/.test(code));
|
2018-10-10 22:03:03 +00:00
|
|
|
```
|
2020-04-29 10:29:13 +00:00
|
|
|
|
2021-01-13 02:31:00 +00:00
|
|
|
# --seed--
|
|
|
|
|
|
|
|
## --seed-contents--
|
|
|
|
|
|
|
|
```js
|
|
|
|
function testElse(val) {
|
2021-10-27 15:10:57 +00:00
|
|
|
let result = "";
|
2021-01-13 02:31:00 +00:00
|
|
|
// Only change code below this line
|
|
|
|
|
|
|
|
if (val > 5) {
|
|
|
|
result = "Bigger than 5";
|
|
|
|
}
|
|
|
|
|
|
|
|
if (val <= 5) {
|
|
|
|
result = "5 or Smaller";
|
|
|
|
}
|
|
|
|
|
|
|
|
// Only change code above this line
|
|
|
|
return result;
|
|
|
|
}
|
|
|
|
|
|
|
|
testElse(4);
|
|
|
|
```
|
|
|
|
|
2020-12-16 07:37:30 +00:00
|
|
|
# --solutions--
|
|
|
|
|
2021-01-13 02:31:00 +00:00
|
|
|
```js
|
|
|
|
function testElse(val) {
|
2021-10-27 15:10:57 +00:00
|
|
|
let result = "";
|
2021-01-13 02:31:00 +00:00
|
|
|
if(val > 5) {
|
|
|
|
result = "Bigger than 5";
|
|
|
|
} else {
|
|
|
|
result = "5 or Smaller";
|
|
|
|
}
|
|
|
|
return result;
|
|
|
|
}
|
|
|
|
```
|