145 lines
4.2 KiB
Markdown
145 lines
4.2 KiB
Markdown
---
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id: bad87fee1348bd9aed108826
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title: 使用 jQuery 选择元素的特定子元素
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challengeType: 6
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forumTopicId: 18315
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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-a-specific-child-of-an-element-using-jquery
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---
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# --description--
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已经看到了 id 属性对于 jQuery 选择器选取标签的便利， 但这并不适用于所有情景。
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幸运的是，jQuery 有一些其他的方法可以选取正确的标签。
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jQuery 可以用 CSS 选择器（CSS Selectors）选取标签。 `target:nth-child(n)` CSS 选择器可以选取指定 class 或者元素类型的的第 n 个标签。
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下面的代码展示了给每个区域（well）的第 3 个标签设置弹跳（bounce）动画效果：
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```js
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$(".target:nth-child(3)").addClass("animated bounce");
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```
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给 well 元素的第二个子元素添加弹跳（bounce）动画效果。 你必须选择具有 `target` class 的元素子项。
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# --hints--
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`target` 元素中的第二个元素应该有弹跳（bounce）动画效果。
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```js
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assert(
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$('.target:nth-child(2)').hasClass('animated') &&
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$('.target:nth-child(2)').hasClass('bounce')
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);
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```
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应该仅两个元素有弹跳（bounce）动画效果。
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```js
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assert($('.animated.bounce').length === 2);
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```
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你应该使用 `:nth-child()` 选择器修改这些元素。
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```js
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assert(code.match(/\:nth-child\(/g));
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```
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应该仅用 jQuery 给元素添加 class。
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```js
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assert(
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code.match(/\$\(".target:nth-child\(2\)"\)/g) ||
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code.match(/\$\('.target:nth-child\(2\)'\)/g) ||
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code.match(/\$\(".target"\).filter\(":nth-child\(2\)"\)/g) ||
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code.match(/\$\('.target'\).filter\(':nth-child\(2\)'\)/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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});
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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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$(".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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