2018-10-10 18:03:03 -04:00
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---
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id: 587d7faa367417b2b2512bd4
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title: Add a Hover Effect to a D3 Element
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challengeType: 6
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videoUrl: ''
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localeTitle: 将悬停效果添加到D3元素
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---
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## Description
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<section id="description">当用户用鼠标悬停在其上时，可以添加突出显示条形的效果。到目前为止，矩形的样式使用内置的D3和SVG方法，但您也可以使用CSS。使用<code>attr()</code>方法在SVG元素上设置CSS类。然后，新类的<code>:hover</code>伪类保存任何悬停效果的样式规则。 </section>
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## Instructions
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<section id="instructions">使用<code>attr()</code>方法向所有<code>rect</code>元素添加一个<code>bar</code>类。将鼠标悬停在其上时，会将条形的<code>fill</code>颜色更改为棕色。 </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: 你的<code>rect</code>元素应该有一类<code>bar</code> 。
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2020-02-18 01:40:55 +09:00
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testString: assert($('rect').attr('class') == "bar");
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2018-10-10 18:03:03 -04:00
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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>
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.bar:hover {
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fill: brown;
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}
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</style>
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<body>
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<script>
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const dataset = [12, 31, 22, 17, 25, 18, 29, 14, 9];
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const w = 500;
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const h = 100;
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const svg = d3.select("body")
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.append("svg")
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.attr("width", w)
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.attr("height", h);
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svg.selectAll("rect")
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.data(dataset)
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.enter()
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.append("rect")
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.attr("x", (d, i) => i * 30)
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.attr("y", (d, i) => h - 3 * d)
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.attr("width", 25)
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.attr("height", (d, i) => 3 * d)
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.attr("fill", "navy")
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// Add your code below this line
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// Add your code above this line
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svg.selectAll("text")
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.data(dataset)
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.enter()
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.append("text")
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.text((d) => d)
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.attr("x", (d, i) => i * 30)
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.attr("y", (d, i) => h - (3 * d) - 3);
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</script>
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</body>
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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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2020-08-13 17:24:35 +02:00
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/section>
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