2018-10-10 18:03:03 -04:00
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---
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id: 587d7faa367417b2b2512bd4
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2021-03-04 09:49:46 -08:00
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title: 给 D3 元素添加悬停效果
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2018-10-10 18:03:03 -04:00
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challengeType: 6
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2020-09-18 00:13:05 +08:00
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forumTopicId: 301469
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2021-01-13 03:31:00 +01:00
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dashedName: add-a-hover-effect-to-a-d3-element
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2018-10-10 18:03:03 -04:00
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---
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2020-12-16 00:37:30 -07:00
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# --description--
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2018-10-10 18:03:03 -04:00
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2021-03-04 09:49:46 -08:00
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我们可以为用户的鼠标悬停行为添加高亮显示的效果。 到目前为止，矩形的样式应用了内置的 D3 和 SVG 方法，但是你也可以使用 CSS 来实现。
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2018-10-10 18:03:03 -04:00
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2021-03-04 09:49:46 -08:00
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你可以使用 `attr()` 方法在 SVG 元素上设置 CSS class。 然后用 `:hover` 伪类为你新添加的 CSS 类设置鼠标悬停的效果。
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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# --instructions--
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2018-10-10 18:03:03 -04:00
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2021-03-04 09:49:46 -08:00
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用 `attr()` 方法给所有的 `rect` 元素都添加 `bar` class。 当鼠标悬停在元素上时，它的 `fill` 将变为棕色。
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2018-10-10 18:03:03 -04:00
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2020-12-16 00:37:30 -07:00
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# --hints--
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2018-10-10 18:03:03 -04:00
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2021-03-04 09:49:46 -08:00
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`rect` 元素应该有 `bar` class。
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2018-10-10 18:03:03 -04:00
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```js
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2021-05-24 00:42:08 -07:00
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assert($('rect').attr('class').trim().split(/\s+/g).includes('bar'));
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2018-10-10 18:03:03 -04:00
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```
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2020-08-13 17:24:35 +02:00
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2021-01-13 03:31:00 +01:00
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# --seed--
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## --seed-contents--
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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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2020-12-16 00:37:30 -07:00
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# --solutions--
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2021-01-13 03:31:00 +01:00
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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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.attr('class', 'bar')
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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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