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

Pie and doughnut charts

Pie and doughnut charts are used to display numerical proportion between data as parts of a whole. Each data value is represented as a slice, which represents a proportional quantity. These charts are very popular but are also widely criticized. Since we don't perceive angles very well, it's much harder to compare data displayed in a pie chart, than in a bar or line chart. Using pie charts to compare only very small sets of data can avoid or reduce these problems.

A pie chart is usually used to display a single dataset. The type property of the chart object should be pie. Doughnut charts are equivalent to pie charts, but they are created with type: doughnut. You can also transform any pie chart into a doughnut by simply changing the dataset property cutoutPercentage to 50 (or some other value different than zero).

Creating a simple pie chart

Let's create a simple pie chart to compare CO2 emissions among the world's greatest polluters for a single year. You can use the...