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---
id: 587d7fa9367417b2b2512bcf
title: Dynamically Change the Height of Each Bar
required:
- src: 'https://cdnjs.cloudflare.com/ajax/libs/d3/4.3.0/d3.min.js'
challengeType: 6
---
## Description
< section id = 'description' >
The height of each bar can be set to the value of the data point in the array, similar to how the < code > x< / code > value was set dynamically.
< blockquote > selection.attr("property", (d, i) => {< br > /* < br > * d is the data point value< br > * i is the index of the data point in the array< br > */< br > })< / blockquote >
< / section >
## Instructions
< section id = 'instructions' >
Change the callback function for the < code > height< / code > attribute to return the data value times 3.
< strong > Note< / strong > < br > Remember that multiplying all data points by the same constant scales the data (like zooming in). It helps to see the differences between bar values in this example.
< / section >
## Tests
< section id = 'tests' >
```yml
- text: The first < code > rect</ code > should have a < code > height</ code > of 36.
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testString: 'assert($(''rect'').eq(0).attr(''height'') == ''36'', ''The first < code > rect< / code > should have a < code > height< / code > of 36.'');'
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- text: The second < code > rect</ code > should have a < code > height</ code > of 93.
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testString: 'assert($(''rect'').eq(1).attr(''height'') == ''93'', ''The second < code > rect< / code > should have a < code > height< / code > of 93.'');'
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- text: The third < code > rect</ code > should have a < code > height</ code > of 66.
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testString: 'assert($(''rect'').eq(2).attr(''height'') == ''66'', ''The third < code > rect< / code > should have a < code > height< / code > of 66.'');'
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- text: The fourth < code > rect</ code > should have a < code > height</ code > of 51.
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testString: 'assert($(''rect'').eq(3).attr(''height'') == ''51'', ''The fourth < code > rect< / code > should have a < code > height< / code > of 51.'');'
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- text: The fifth < code > rect</ code > should have a < code > height</ code > of 75.
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testString: 'assert($(''rect'').eq(4).attr(''height'') == ''75'', ''The fifth < code > rect< / code > should have a < code > height< / code > of 75.'');'
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- text: The sixth < code > rect</ code > should have a < code > height</ code > of 54.
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testString: 'assert($(''rect'').eq(5).attr(''height'') == ''54'', ''The sixth < code > rect< / code > should have a < code > height< / code > of 54.'');'
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- text: The seventh < code > rect</ code > should have a < code > height</ code > of 87.
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testString: 'assert($(''rect'').eq(6).attr(''height'') == ''87'', ''The seventh < code > rect< / code > should have a < code > height< / code > of 87.'');'
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- text: The eighth < code > rect</ code > should have a < code > height</ code > of 42.
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testString: 'assert($(''rect'').eq(7).attr(''height'') == ''42'', ''The eighth < code > rect< / code > should have a < code > height< / code > of 42.'');'
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- text: The ninth < code > rect</ code > should have a < code > height</ code > of 27.
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testString: 'assert($(''rect'').eq(8).attr(''height'') == ''27'', ''The ninth < code > rect< / code > should have a < code > height< / code > of 27.'');'
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```
< / section >
## Challenge Seed
< section id = 'challengeSeed' >
< div id = 'html-seed' >
```html
< 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", 0)
.attr("width", 25)
.attr("height", (d, i) => {
// Add your code below this line
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// Add your code above this line
});
< / script >
< / body >
```
< / div >
< / section >
## Solution
< section id = 'solution' >
```js
// solution required
```
< / section >
