Book Image

Learn Chart.js

By : Helder da Rocha
Book Image

Learn Chart.js

By: Helder da Rocha

Overview of this book

Chart.js is a free, open-source data visualization library, maintained by an active community of developers in GitHub, where it rates as the second most popular data visualization library. If you want to quickly create responsive Web-based data visualizations for the Web, Chart.js is a great choice. This book guides the reader through dozens of practical examples, complete with code you can run and modify as you wish. It is a practical hands-on introduction to Chart.js. If you have basic knowledge of HTML, CSS and JavaScript you can learn to create beautiful interactive Web Canvas-based visualizations for your data using Chart.js. This book will help you set up Chart.js in a Web page and show how to create each one of the eight Chart.js chart types. You will also learn how to configure most properties that override Chart’s default styles and behaviors. Practical applications of Chart.js are exemplified using real data files obtained from public data portals. You will learn how to load, parse, filter and select the data you wish to display from those files. You will also learn how to create visualizations that reveal patterns in the data. This book is based on Chart.js version 2.7.3 and ES2015 JavaScript. By the end of the book, you will be able to create beautiful, efficient and interactive data visualizations for the Web using Chart.js.
Table of Contents (14 chapters)
Title Page
Copyright and Credits
About Packt

Adding text elements and labels

You can always add captions and titles outside your chart, using plain HTML or JavaScript. However, Chart.js also includes properties that draw and configure text elements inside the canvas as part of the chart. If the properties don't give you enough flexibility, you can use callbacks to filter or generate labels. If tooltips, titles, and legends aren't enough, you can also use plugins to add labels to bars, slices, and lines. You can even draw over the chart using plain HTML Canvas. This section will explore some of these techniques.



Legends and labels

Legends are displayed by default in bar, line, pie and doughnut charts. They appear as a list of labeled, colored boxes that relate to the color of the lines, bars, or slices represented by a dataset, and they are rendered on the screen even when there is a single dataset. In such cases, you may wish to hide them. You can also tune several other properties and callbacks. The most important properties are listed...