99 lines
2.4 KiB
Markdown
99 lines
2.4 KiB
Markdown
---
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id: 587d7fa7367417b2b2512bc8
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title: Add Classes with D3
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challengeType: 6
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---
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## Description
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<section id='description'>
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Using a lot of inline styles on HTML elements gets hard to manage, even for smaller apps. It's easier to add a class to elements and style that class one time using CSS rules. D3 has the <code>attr()</code> method to add any HTML attribute to an element, including a class name.
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The <code>attr()</code> method works the same way that <code>style()</code> does. It takes comma-separated values, and can use a callback function. Here's an example to add a class of "container" to a selection:
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<code>selection.attr("class", "container");</code>
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Note that the "class" parameter will remain the same whenever you need to add a class and only the "container" parameter will change.
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</section>
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## Instructions
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<section id='instructions'>
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Add the <code>attr()</code> method to the code in the editor and put a class of <code>bar</code> on the <code>div</code> elements.
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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: Your <code>div</code> elements should have a class of <code>bar</code>.
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testString: assert($('div').attr('class') == "bar", 'Your <code>div</code> elements should have a class of <code>bar</code>.');
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- text: Your code should use the <code>attr()</code> method.
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testString: assert(code.match(/\.attr/g), 'Your code should use the <code>attr()</code> method.');
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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 {
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width: 25px;
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height: 100px;
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display: inline-block;
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background-color: blue;
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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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d3.select("body").selectAll("div")
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.data(dataset)
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.enter()
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.append("div")
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// Add your code below this line
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// Add your code above this line
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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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```html
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<style>
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.bar {
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width: 25px;
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height: 100px;
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display: inline-block;
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background-color: blue;
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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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d3.select("body").selectAll("div")
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.data(dataset)
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.enter()
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.append("div")
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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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</script>
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</body>
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```
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</section>
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