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											2018-10-10 18:03:03 -04:00
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							|  |  |  | id: 56533eb9ac21ba0edf2244da | 
					
						
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											2021-03-14 21:20:39 -06:00
										 |  |  | title: 介绍 else 语句 | 
					
						
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											2018-10-10 18:03:03 -04:00
										 |  |  | challengeType: 1 | 
					
						
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										 |  |  | videoUrl: 'https://scrimba.com/c/cek4Efq' | 
					
						
							|  |  |  | forumTopicId: 18207 | 
					
						
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											2021-01-13 03:31:00 +01:00
										 |  |  | dashedName: introducing-else-statements | 
					
						
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											2018-10-10 18:03:03 -04:00
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										 |  |  | # --description--
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										 |  |  | 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。 | 
					
						
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							|  |  |  | ```js | 
					
						
							|  |  |  | if (num > 10) { | 
					
						
							|  |  |  |   return "Bigger than 10"; | 
					
						
							|  |  |  | } else { | 
					
						
							|  |  |  |   return "10 or Less"; | 
					
						
							|  |  |  | } | 
					
						
							|  |  |  | ``` | 
					
						
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										 |  |  | # --instructions--
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										 |  |  | 请把多个 `if` 语句合并为一个 `if/else` 语句。 | 
					
						
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										 |  |  | # --hints--
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										 |  |  | 应该只有一个 `if` 语句。 | 
					
						
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							|  |  |  | ```js | 
					
						
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										 |  |  | assert(code.match(/if/g).length === 1); | 
					
						
							|  |  |  | ``` | 
					
						
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										 |  |  | 应该使用一个 `else` 语句。 | 
					
						
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										 |  |  | ```js | 
					
						
							|  |  |  | assert(/else/g.test(code)); | 
					
						
							|  |  |  | ``` | 
					
						
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										 |  |  | `testElse(4)` 应该返回字符串 `5 or Smaller` | 
					
						
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										 |  |  | ```js | 
					
						
							|  |  |  | assert(testElse(4) === '5 or Smaller'); | 
					
						
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										 |  |  | ``` | 
					
						
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										 |  |  | `testElse(5)` 应该返回字符串 `5 or Smaller` | 
					
						
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										 |  |  | ```js | 
					
						
							|  |  |  | assert(testElse(5) === '5 or Smaller'); | 
					
						
							|  |  |  | ``` | 
					
						
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										 |  |  | `testElse(6)` 应该返回字符串 `Bigger than 5` | 
					
						
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							|  |  |  | ```js | 
					
						
							|  |  |  | assert(testElse(6) === 'Bigger than 5'); | 
					
						
							|  |  |  | ``` | 
					
						
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										 |  |  | `testElse(10)` 应该返回字符串 `Bigger than 5` | 
					
						
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										 |  |  | ```js | 
					
						
							|  |  |  | assert(testElse(10) === 'Bigger than 5'); | 
					
						
							|  |  |  | ``` | 
					
						
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										 |  |  | 不要修改相应注释的上面或下面的代码。 | 
					
						
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											2020-04-29 18:29:13 +08:00
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										 |  |  | ```js | 
					
						
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										 |  |  | assert(/var result = "";/.test(code) && /return result;/.test(code)); | 
					
						
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										 |  |  | ``` | 
					
						
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											2021-01-13 03:31:00 +01:00
										 |  |  | # --seed--
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							|  |  |  | ## --seed-contents--
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							|  |  |  | ```js | 
					
						
							|  |  |  | function testElse(val) { | 
					
						
							|  |  |  |   var result = ""; | 
					
						
							|  |  |  |   // Only change code below this line | 
					
						
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							|  |  |  |   if (val > 5) { | 
					
						
							|  |  |  |     result = "Bigger than 5"; | 
					
						
							|  |  |  |   } | 
					
						
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							|  |  |  |   if (val <= 5) { | 
					
						
							|  |  |  |     result = "5 or Smaller"; | 
					
						
							|  |  |  |   } | 
					
						
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							|  |  |  |   // Only change code above this line | 
					
						
							|  |  |  |   return result; | 
					
						
							|  |  |  | } | 
					
						
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							|  |  |  | testElse(4); | 
					
						
							|  |  |  | ``` | 
					
						
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										 |  |  | # --solutions--
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										 |  |  | ```js | 
					
						
							|  |  |  | function testElse(val) { | 
					
						
							|  |  |  |   var result = ""; | 
					
						
							|  |  |  |   if(val > 5) { | 
					
						
							|  |  |  |     result = "Bigger than 5"; | 
					
						
							|  |  |  |   } else { | 
					
						
							|  |  |  |     result = "5 or Smaller"; | 
					
						
							|  |  |  |   } | 
					
						
							|  |  |  |   return result; | 
					
						
							|  |  |  | } | 
					
						
							|  |  |  | ``` |