If语句用于在代码中做出决定。关键字if告诉JavaScript在括号中定义的特定条件下执行花括号中的代码。这些条件称为Boolean条件,它们可能只是true或false 。当条件计算结果为true ,程序将执行花括号内的语句。当布尔条件的计算结果为false ,大括号内的语句将不会执行。 伪代码 if( condition为true ){例
声明被执行
}
功能测试(myCondition){当使用值
if(myCondition){
回归“这是真的”;
}
返回“这是假的”;
}
测试(真); //返回“这是真的”
测试(假); //返回“这是假的”
true调用test , if语句将评估myCondition以查看它是否为true 。因为它是true ,函数返回"It was true" 。当我们使用false值调用test时, myCondition 不为 true并且不执行花括号中的语句,函数返回"It was false" 。 if语句"Yes, that was true"如果参数wasThatTrue为true则返回"Yes, that was true" "No, that was false"否则返回"No, that was false" 。 trueOrFalse应该是一个函数
testString: 'assert(typeof trueOrFalse === "function", "trueOrFalse should be a function");'
- text: trueOrFalse(true)应该返回一个字符串
testString: 'assert(typeof trueOrFalse(true) === "string", "trueOrFalse(true) should return a string");'
- text: trueOrFalse(false)应该返回一个字符串
testString: 'assert(typeof trueOrFalse(false) === "string", "trueOrFalse(false) should return a string");'
- text: trueOrFalse(true)应该返回“是的,那是真的”
testString: 'assert(trueOrFalse(true) === "Yes, that was true", "trueOrFalse(true) should return "Yes, that was true"");'
- text: trueOrFalse(false)应该返回“No,that was false”
testString: 'assert(trueOrFalse(false) === "No, that was false", "trueOrFalse(false) should return "No, that was false"");'
```