138 lines
4.2 KiB
Markdown
138 lines
4.2 KiB
Markdown
---
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id: bad87fee1348bd9aed008826
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title: 使用 jQuery 选择偶数元素
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challengeType: 6
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forumTopicId: 18318
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required:
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-
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link: 'https://cdnjs.cloudflare.com/ajax/libs/animate.css/3.2.0/animate.css'
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dashedName: target-even-elements-using-jquery
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---
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# --description--
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也可以用基于位置的奇 `:odd` 和偶 `:even` 选择器选取标签。
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注意，jQuery 是零索引（zero-indexed）的，这意味着第 1 个标签的位置编号是 0。 这有点混乱和反常——`:odd` 表示选择第 2 个标签（位置编号 1），第 4 个标签（位置编号 3）……等等，以此类推。
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下面的代码展示了选取所有 `target` class 元素的奇数元素并设置 sheke 效果：
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`$(".target:odd").addClass("animated shake");`
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尝试选取所有 `target` class 元素的偶数元素并给它们设置 `animated` 和 `shake` class。 要考虑到**偶（even）**指的是标签位置编号是从 0 开始的。
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# --hints--
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所有的 `target` 标签应该抖动。
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```js
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assert(
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$('.target:even').hasClass('animated') && $('.target:even').hasClass('shake')
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);
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```
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应该用 `:even` 选择器修改这些标签。
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```js
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assert(code.match(/\:even/g));
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```
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应该仅用 jQuery 给标签添加类。
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```js
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assert(
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code.match(/\$\(".target:even"\)/g) ||
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code.match(/\$\('.target:even'\)/g) ||
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code.match(/\$\(".target"\).filter\(":even"\)/g) ||
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code.match(/\$\('.target'\).filter\(':even'\)/g)
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);
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```
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# --seed--
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## --seed-contents--
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```html
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<script>
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$(document).ready(function() {
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$("#target1").css("color", "red");
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$("#target1").prop("disabled", true);
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$("#target4").remove();
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$("#target2").appendTo("#right-well");
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$("#target5").clone().appendTo("#left-well");
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$("#target1").parent().css("background-color", "red");
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$("#right-well").children().css("color", "orange");
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$("#left-well").children().css("color", "green");
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$(".target:nth-child(2)").addClass("animated bounce");
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});
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</script>
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<!-- Only change code above this line -->
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<div class="container-fluid">
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<h3 class="text-primary text-center">jQuery Playground</h3>
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<div class="row">
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<div class="col-xs-6">
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<h4>#left-well</h4>
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<div class="well" id="left-well">
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<button class="btn btn-default target" id="target1">#target1</button>
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<button class="btn btn-default target" id="target2">#target2</button>
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<button class="btn btn-default target" id="target3">#target3</button>
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</div>
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</div>
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<div class="col-xs-6">
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<h4>#right-well</h4>
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<div class="well" id="right-well">
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<button class="btn btn-default target" id="target4">#target4</button>
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<button class="btn btn-default target" id="target5">#target5</button>
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<button class="btn btn-default target" id="target6">#target6</button>
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</div>
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</div>
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</div>
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</div>
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```
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# --solutions--
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```html
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<script>
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$(document).ready(function() {
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$("#target1").css("color", "red");
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$("#target1").prop("disabled", true);
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$("#target4").remove();
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$("#target2").appendTo("#right-well");
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$("#target5").clone().appendTo("#left-well");
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$("#target1").parent().css("background-color", "red");
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$("#right-well").children().css("color", "orange");
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$("#left-well").children().css("color", "green");
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$(".target:nth-child(2)").addClass("animated bounce");
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$(".target:even").addClass("animated shake");
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});
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</script>
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<!-- Only change code above this line -->
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<div class="container-fluid">
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<h3 class="text-primary text-center">jQuery Playground</h3>
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<div class="row">
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<div class="col-xs-6">
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<h4>#left-well</h4>
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<div class="well" id="left-well">
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<button class="btn btn-default target" id="target1">#target1</button>
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<button class="btn btn-default target" id="target2">#target2</button>
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<button class="btn btn-default target" id="target3">#target3</button>
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</div>
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</div>
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<div class="col-xs-6">
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<h4>#right-well</h4>
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<div class="well" id="right-well">
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<button class="btn btn-default target" id="target4">#target4</button>
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<button class="btn btn-default target" id="target5">#target5</button>
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<button class="btn btn-default target" id="target6">#target6</button>
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</div>
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</div>
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</div>
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</div>
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```
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