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---
id: 587d7faa367417b2b2512bd6
title: Add a Tooltip to a D3 Element
required:
- src: 'https://cdnjs.cloudflare.com/ajax/libs/d3/4.3.0/d3.min.js'
challengeType: 6
---
## Description
< section id = 'description' >
A tooltip shows more information about an item on a page when the user hovers over that item. There are several ways to add a tooltip to a visualization, this challenge uses the SVG < code > title< / code > element.
< code > title< / code > pairs with the < code > text()< / code > method to dynamically add data to the bars.
< / section >
## Instructions
< section id = 'instructions' >
Append a < code > title< / code > element under each < code > rect< / code > node. Then call the < code > text()< / code > method with a callback function so the text displays the data value.
< / section >
## Tests
< section id = 'tests' >
```yml
tests:
- text: Your code should have 9 < code > title</ code > elements.
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testString: assert($('title').length == 9, 'Your code should have 9 < code > title< / code > elements.');
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- text: The first < code > title</ code > element should have tooltip text of 12.
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testString: assert($('title').eq(0).text() == '12', 'The first < code > title< / code > element should have tooltip text of 12.');
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- text: The second < code > title</ code > element should have tooltip text of 31.
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testString: assert($('title').eq(1).text() == '31', 'The second < code > title< / code > element should have tooltip text of 31.');
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- text: The third < code > title</ code > element should have tooltip text of 22.
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testString: assert($('title').eq(2).text() == '22', 'The third < code > title< / code > element should have tooltip text of 22.');
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- text: The fourth < code > title</ code > element should have tooltip text of 17.
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testString: assert($('title').eq(3).text() == '17', 'The fourth < code > title< / code > element should have tooltip text of 17.');
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- text: The fifth < code > title</ code > element should have tooltip text of 25.
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testString: assert($('title').eq(4).text() == '25', 'The fifth < code > title< / code > element should have tooltip text of 25.');
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- text: The sixth < code > title</ code > element should have tooltip text of 18.
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testString: assert($('title').eq(5).text() == '18', 'The sixth < code > title< / code > element should have tooltip text of 18.');
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- text: The seventh < code > title</ code > element should have tooltip text of 29.
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testString: assert($('title').eq(6).text() == '29', 'The seventh < code > title< / code > element should have tooltip text of 29.');
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- text: The eighth < code > title</ code > element should have tooltip text of 14.
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testString: assert($('title').eq(7).text() == '14', 'The eighth < code > title< / code > element should have tooltip text of 14.');
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- text: The ninth < code > title</ code > element should have tooltip text of 9.
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testString: assert($('title').eq(8).text() == '9', 'The ninth < code > title< / code > element should have tooltip text of 9.');
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```
< / section >
## Challenge Seed
< section id = 'challengeSeed' >
< div id = 'html-seed' >
```html
< style >
.bar:hover {
fill: brown;
}
< / style >
< body >
< script >
const dataset = [12, 31, 22, 17, 25, 18, 29, 14, 9];
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const w = 500;
const h = 100;
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const svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
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svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr("x", (d, i) => i * 30)
.attr("y", (d, i) => h - 3 * d)
.attr("width", 25)
.attr("height", (d, i) => d * 3)
.attr("fill", "navy")
.attr("class", "bar")
// Add your code below this line
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// Add your code above this line
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svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text((d) => d)
.attr("x", (d, i) => i * 30)
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.attr("y", (d, i) => h - (d * 3 + 3))
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< / script >
< / body >
```
< / div >
< / section >
## Solution
< section id = 'solution' >
```js
// solution required
```
< / section >
