86 lines
3.6 KiB
Markdown
86 lines
3.6 KiB
Markdown
---
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id: 587d7fa7367417b2b2512bc5
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title: Work with Dynamic Data in 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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The last two challenges cover the basics of displaying data dynamically with D3 using the <code>data()</code> and <code>enter()</code> methods. These methods take a data set and, together with the <code>append()</code> method, create a new DOM element for each entry in the data set.
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In the previous challenge, you created a new <code>h2</code> element for each item in the <code>dataset</code> array, but they all contained the same text, "New Title". This is because you have not made use of the data that is bound to each of the <code>h2</code> elements.
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The D3 <code>text()</code> method can take a string or a callback function as an argument:
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<code>selection.text((d) => d)</code>
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In the example above, the parameter <code>d</code> refers to a single entry in the dataset that a selection is bound to.
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Using the current example as context, the first <code>h2</code> element is bound to 12, the second <code>h2</code> element is bound to 31, the third <code>h2</code> element is bound to 22, and so on.
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</section>
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## Instructions
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<section id='instructions'>
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Change the <code>text()</code> method so that each <code>h2</code> element displays the corresponding value from the <code>dataset</code> array with a single space and "USD". For example, the first heading should be "12 USD".
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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: The first <code>h2</code> should have the text "12 USD".
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testString: assert($('h2').eq(0).text() == "12 USD", 'The first <code>h2</code> should have the text "12 USD".');
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- text: The second <code>h2</code> should have the text "31 USD".
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testString: assert($('h2').eq(1).text() == "31 USD", 'The second <code>h2</code> should have the text "31 USD".');
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- text: The third <code>h2</code> should have the text "22 USD".
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testString: assert($('h2').eq(2).text() == "22 USD", 'The third <code>h2</code> should have the text "22 USD".');
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- text: The fourth <code>h2</code> should have the text "17 USD".
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testString: assert($('h2').eq(3).text() == "17 USD", 'The fourth <code>h2</code> should have the text "17 USD".');
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- text: The fifth <code>h2</code> should have the text "25 USD".
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testString: assert($('h2').eq(4).text() == "25 USD", 'The fifth <code>h2</code> should have the text "25 USD".');
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- text: The sixth <code>h2</code> should have the text "18 USD".
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testString: assert($('h2').eq(5).text() == "18 USD", 'The sixth <code>h2</code> should have the text "18 USD".');
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- text: The seventh <code>h2</code> should have the text "29 USD".
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testString: assert($('h2').eq(6).text() == "29 USD", 'The seventh <code>h2</code> should have the text "29 USD".');
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- text: The eighth <code>h2</code> should have the text "14 USD".
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testString: assert($('h2').eq(7).text() == "14 USD", 'The eighth <code>h2</code> should have the text "14 USD".');
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- text: The ninth <code>h2</code> should have the text "9 USD".
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testString: assert($('h2').eq(8).text() == "9 USD", 'The ninth <code>h2</code> should have the text "9 USD".');
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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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<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("h2")
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.data(dataset)
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.enter()
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.append("h2")
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// Add your code below this line
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.text("New Title");
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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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```js
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// solution required
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```
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</section>
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