110 lines
3.0 KiB
Markdown
110 lines
3.0 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244be
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title: Global Scope and Functions
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challengeType: 1
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videoUrl: ''
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localeTitle: 全球范围和职能
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---
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## Description
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<section id="description">在JavaScript中， <dfn>范围</dfn>是指变量的可见性。在功能块之外定义的变量具有<dfn>全局</dfn>范围。这意味着，它们可以在JavaScript代码中随处可见。在没有<code>var</code>关键字的情况下使用的变量将在<code>global</code>范围内自动创建。这可能会在代码中的其他位置或再次运行函数时产生意外后果。您应该始终使用<code>var</code>声明变量。 </section>
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## Instructions
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<section id="instructions">使用<code>var</code> ，在任何函数之外声明一个<code>global</code>变量<code>myGlobal</code> 。使用值<code>10</code>初始化它。在函数<code>fun1</code>内部，在<strong><em>不</em></strong>使用<code>var</code>关键字的<strong><em>情况下</em></strong>为<code>oopsGlobal</code>分配<code>5</code> 。 </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: 应该定义<code>myGlobal</code>
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testString: 'assert(typeof myGlobal != "undefined", "<code>myGlobal</code> should be defined");'
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- text: <code>myGlobal</code>的值应为<code>10</code>
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testString: 'assert(myGlobal === 10, "<code>myGlobal</code> should have a value of <code>10</code>");'
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- text: 应使用<code>var</code>关键字声明<code>myGlobal</code>
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testString: 'assert(/var\s+myGlobal/.test(code), "<code>myGlobal</code> should be declared using the <code>var</code> keyword");'
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- text: <code>oopsGlobal</code>应该是一个全局变量，其值为<code>5</code>
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testString: 'assert(typeof oopsGlobal != "undefined" && oopsGlobal === 5, "<code>oopsGlobal</code> should be a global variable and have a value of <code>5</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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// Declare your variable here
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function fun1() {
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// Assign 5 to oopsGlobal Here
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}
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// Only change code above this line
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function fun2() {
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var output = "";
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if (typeof myGlobal != "undefined") {
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output += "myGlobal: " + myGlobal;
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}
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if (typeof oopsGlobal != "undefined") {
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output += " oopsGlobal: " + oopsGlobal;
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}
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console.log(output);
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}
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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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logOutput = message;
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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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var oopsGlobal;
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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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console.info('after the test');
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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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// solution required
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```
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</section>
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