135 lines
3.4 KiB
Markdown
135 lines
3.4 KiB
Markdown
---
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id: 587d7dbe367417b2b2512bb8
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title: Use @if and @else to Add Logic To Your Styles
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challengeType: 0
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forumTopicId: 301463
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localeTitle: 使用 @if 和 @else 为你的样式添加逻辑
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---
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## Description
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<section id='description'>
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Sass 中的<code>@if</code>指令对于测试特定情况非常有用--它的工作方式与 JavaScript</code>中的<code>if</code>语句类似。
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```scss
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@mixin make-bold($bool) {
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@if $bool == true {
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font-weight: bold;
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}
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}
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```
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类似 JavaScript,你可以在 Sass 中使用<code>@else if</code>和<code>@else</code>添加更多条件:
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```scss
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@mixin text-effect($val) {
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@if $val == danger {
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color: red;
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}
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@else if $val == alert {
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color: yellow;
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}
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@else if $val == success {
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color: green;
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}
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@else {
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color: black;
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}
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}
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```
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</section>
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## Instructions
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<section id='instructions'>
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创建一个名为<code>border-stroke</code>的<code>mixin</code>,它接受一个参数<code>$val</code>。<code>mixin</code>应使用<code>@if</code>,<code>@else if</code>和<code>@else</code>检查以下条件:
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```scss
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light - 1px solid black
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medium - 3px solid black
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heavy - 6px solid black
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```
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如果 <code>$val</code> 不是 <code>light</code>、<code>medium</code> 或者 <code>heavy</code>,border 应该设置为 <code>none</code>。
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: 你应该声明一个名为<code>border-stroke</code>的<code>mixin</code>,它有一个名为<code>$val</code>的参数。
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testString: assert(code.match(/@mixin\s+?border-stroke\s*?\(\s*?\$val\s*?\)\s*?{/gi));
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- text: <code>mixin</code>应该有一个<code>@if</code>语句来检查<code>$val</code>是否很轻,并将<code>border</code>设置为 1px 纯黑色。
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testString: assert(code.match(/@if\s+?\$val\s*?===?\s*?light\s*?{\s*?border\s*?:\s*?1px\s+?solid\s+?black\s*?;\s*?}/gi));
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- text: <code>mixin</code>应该有一个<code>@else if</code>语句来检查<code>$val</code>是否中等,并设置<code>border</code>为3px 纯黑色。
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testString: assert(code.match(/@else\s+?if\s+?\$val\s*?===?\s*?medium\s*?{\s*?border\s*?:\s*?3px\s+?solid\s+?black\s*?;\s*?}/gi));
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- text: <code>mixin</code>应该有一个<code>@else if</code>语句来检查<code>$val</code>是否很重,并设置<code>border</code>为6px 纯黑色。
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testString: assert(code.match(/@else\s+?if\s+?\$val\s*?===?\s*?heavy\s*?{\s*?border\s*?:\s*?6px\s+?solid\s+?black\s*?;\s*?}/gi));
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- text: <code>mixin</code>应该有一个<code>@else</code>语句来将<code>border</code>设置为 none。
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testString: assert(code.match(/@else\s*?{\s*?border\s*?:\s*?none\s*?;\s*?}/gi));
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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='html-seed'>
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```html
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<style type='text/sass'>
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#box {
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width: 150px;
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height: 150px;
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background-color: red;
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@include border-stroke(medium);
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}
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</style>
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<div id="box"></div>
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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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```html
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<style type='text/sass'>
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@mixin border-stroke($val) {
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@if $val == light {
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border: 1px solid black;
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}
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@else if $val == medium {
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border: 3px solid black;
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}
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@else if $val == heavy {
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border: 6px solid black;
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}
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@else {
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border: none;
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}
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}
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#box {
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width: 150px;
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height: 150px;
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background-color: red;
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@include border-stroke(medium);
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}
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</style>
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<div id="box"></div>
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```
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</section>
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