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

Scriptable properties

Tooltips have three properties that receive functions. One allows you to replace the Canvas-generated tooltips with your own custom HTML tooltips. The other two allow sorting of tooltip items (when several items appear in a single tooltip) and filtering. These properties are listed as follows:






Used to generate custom HTML tooltips. See the Custom HTML tooltips section on HTML tooltips in this chapter.


(item, data); array of datasets in data.datasets; array of labels in data.labels; item.x and item.y contain coordinates of the value point, item.xLabel and item.yLabel the labels in each axis, item.index is the index of the item in the dataset, and item.datasetIndex is the index of its dataset.

A function that returns true or false and is called before rendering a tooltip item. If it returns false, the item will not be rendered.


(item1, item2); each parameter is an item object with the following properties: x, y...