--- id: cf1111c1c12feddfaeb3bdef title: Use Conditional Logic with If Statements challengeType: 1 videoUrl: '' localeTitle: 使用条件逻辑和If语句 --- ## Description <section id="description"> <code>If</code>语句用于在代码中做出决定。关键字<code>if</code>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<code>Boolean</code>条件,它们可能只是<code>true</code>或<code>false</code> 。当条件计算结果为<code>true</code> ,程序将执行花括号内的语句。当布尔条件的计算结果为<code>false</code> ,大括号内的语句将不会执行。 <strong>伪代码</strong> <blockquote> if( <i>condition为true</i> ){ <br> <i>声明被执行</i> <br> } </blockquote> <strong>例</strong> <blockquote>功能测试(myCondition){ <br> if(myCondition){ <br>回归“这是真的”; <br> } <br>返回“这是假的”; <br> } <br>测试(真); //返回“这是真的” <br>测试(假); //返回“这是假的” </blockquote>当使用值<code>true</code>调用<code>test</code> , <code>if</code>语句将评估<code>myCondition</code>以查看它是否为<code>true</code> 。因为它是<code>true</code> ,函数返回<code>"It was true"</code> 。当我们使用<code>false</code>值调用<code>test</code>时, <code>myCondition</code> <em>不为</em> <code>true</code>并且不执行花括号中的语句,函数返回<code>"It was false"</code> 。 </section> ## Instructions <section id="instructions">在函数内部创建一个<code>if</code>语句<code>"Yes, that was true"</code>如果参数<code>wasThatTrue</code>为<code>true</code>则返回<code>"Yes, that was true"</code> <code>"No, that was false"</code>否则返回<code>"No, that was false"</code> 。 </section> ## Tests <section id='tests'> ```yml tests: - text: <code>trueOrFalse</code>应该是一个函数 testString: 'assert(typeof trueOrFalse === "function", "<code>trueOrFalse</code> should be a function");' - text: <code>trueOrFalse(true)</code>应该返回一个字符串 testString: 'assert(typeof trueOrFalse(true) === "string", "<code>trueOrFalse(true)</code> should return a string");' - text: <code>trueOrFalse(false)</code>应该返回一个字符串 testString: 'assert(typeof trueOrFalse(false) === "string", "<code>trueOrFalse(false)</code> should return a string");' - text: <code>trueOrFalse(true)</code>应该返回“是的,那是真的” testString: 'assert(trueOrFalse(true) === "Yes, that was true", "<code>trueOrFalse(true)</code> should return "Yes, that was true"");' - text: <code>trueOrFalse(false)</code>应该返回“No,that was false” testString: 'assert(trueOrFalse(false) === "No, that was false", "<code>trueOrFalse(false)</code> should return "No, that was false"");' ``` </section> ## Challenge Seed <section id='challengeSeed'> <div id='js-seed'> ```js // Example function ourTrueOrFalse(isItTrue) { if (isItTrue) { return "Yes, it's true"; } return "No, it's false"; } // Setup function trueOrFalse(wasThatTrue) { // Only change code below this line. // Only change code above this line. } // Change this value to test trueOrFalse(true); ``` </div> </section> ## Solution <section id='solution'> ```js // solution required ``` </section>