---
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
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 title
element.
title
pairs with the text()
method to dynamically add data to the bars.
## Instructions
Append a title
element under each rect
node. Then call the text()
method with a callback function so the text displays the data value.
## Tests
```yml
tests:
- text: Your code should have 9 title
elements.
testString: 'assert($(''title'').length == 9, ''Your code should have 9 title
elements.'');'
- text: The first title
element should have tooltip text of 12.
testString: 'assert($(''title'').eq(0).text() == ''12'', ''The first title
element should have tooltip text of 12.'');'
- text: The second title
element should have tooltip text of 31.
testString: 'assert($(''title'').eq(1).text() == ''31'', ''The second title
element should have tooltip text of 31.'');'
- text: The third title
element should have tooltip text of 22.
testString: 'assert($(''title'').eq(2).text() == ''22'', ''The third title
element should have tooltip text of 22.'');'
- text: The fourth title
element should have tooltip text of 17.
testString: 'assert($(''title'').eq(3).text() == ''17'', ''The fourth title
element should have tooltip text of 17.'');'
- text: The fifth title
element should have tooltip text of 25.
testString: 'assert($(''title'').eq(4).text() == ''25'', ''The fifth title
element should have tooltip text of 25.'');'
- text: The sixth title
element should have tooltip text of 18.
testString: 'assert($(''title'').eq(5).text() == ''18'', ''The sixth title
element should have tooltip text of 18.'');'
- text: The seventh title
element should have tooltip text of 29.
testString: 'assert($(''title'').eq(6).text() == ''29'', ''The seventh title
element should have tooltip text of 29.'');'
- text: The eighth title
element should have tooltip text of 14.
testString: 'assert($(''title'').eq(7).text() == ''14'', ''The eighth title
element should have tooltip text of 14.'');'
- text: The ninth title
element should have tooltip text of 9.
testString: 'assert($(''title'').eq(8).text() == ''9'', ''The ninth title
element should have tooltip text of 9.'');'
```
## Challenge Seed
## Solution
```js
// solution required
```