124 lines
3.2 KiB
Markdown
124 lines
3.2 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244bd
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cy8rahW'
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forumTopicId: 18254
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title: 将值传递给带有参数的函数
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---
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## Description
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<section id='description'>
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函数的参数<code>parameters</code>在函数中充当占位符(也叫形参)的作用，参数可以为一个或多个。调用一个函数时所传入的参数为实参，实参决定着形参真正的值。简单理解：形参即形式、实参即内容。
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这是带有两个参数的函数，<code>param1</code>和<code>param2</code>：
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```js
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function testFun(param1, param2) {
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console.log(param1, param2);
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}
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```
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接着我们调用<code>testFun</code>：
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<code>testFun("Hello", "World");</code>
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我们传递了两个参数，<code>"Hello"</code>和<code>"World"</code>。在函数内部，<code>param1</code>等于“Hello”，<code>param2</code>等于“World”。请注意，<code>testFun</code>函数可以多次调用，每次调用时传递的参数会决定形参的实际值。
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</section>
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## Instructions
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<section id='instructions'>
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<ol><li>创建一个名为<code>functionWithArgs</code>的函数，它可以接收两个参数，计算参数的和，将结果输出到控制台。</li><li>调用这个函数。</li></ol>
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: <code>functionWithArgs</code>应该是一个函数。
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testString: assert(typeof functionWithArgs === 'function');
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- text: <code>functionWithArgs(1,2)</code>应该输出<code>3</code>。
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testString: if(typeof functionWithArgs === "function") { capture(); functionWithArgs(1,2); uncapture(); } assert(logOutput == 3);
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- text: <code>functionWithArgs(7,9)</code>应该输出<code>16</code>。
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testString: if(typeof functionWithArgs === "function") { capture(); functionWithArgs(7,9); uncapture(); } assert(logOutput == 16);
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- text: 在你定义<code>functionWithArgs</code>之后记得调用它。
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testString: assert(/^\s*functionWithArgs\s*\(\s*\d+\s*,\s*\d+\s*\)\s*;?/m.test(code));
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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// Example
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function ourFunctionWithArgs(a, b) {
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console.log(a - b);
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}
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ourFunctionWithArgs(10, 5); // Outputs 5
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// Only change code below this line.
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```
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</div>
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### Before Test
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<div id='js-setup'>
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```js
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var logOutput = "";
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var originalConsole = console
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function capture() {
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var nativeLog = console.log;
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console.log = function (message) {
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if(message) logOutput = JSON.stringify(message).trim();
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if(nativeLog.apply) {
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nativeLog.apply(originalConsole, arguments);
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} else {
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var nativeMsg = Array.prototype.slice.apply(arguments).join(' ');
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nativeLog(nativeMsg);
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}
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};
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}
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function uncapture() {
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console.log = originalConsole.log;
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}
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capture();
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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uncapture();
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if (typeof functionWithArgs !== "function") {
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(function() { return "functionWithArgs is not defined"; })();
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} else {
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(function() { return logOutput || "console.log never called"; })();
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}
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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function functionWithArgs(a, b) {
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console.log(a + b);
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}
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functionWithArgs(10, 5);
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```
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</section>
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