Book Image

Learning D3.js 5 Mapping - Second Edition

By : Thomas Newton, Oscar Villarreal, Lars Verspohl
Book Image

Learning D3.js 5 Mapping - Second Edition

By: Thomas Newton, Oscar Villarreal, Lars Verspohl

Overview of this book

D3.js is a visualization library used for the creation and control of dynamic and interactive graphical forms. It is a library used to manipulate HTML and SVG documents as well as the Canvas element based on data. Using D3.js, developers can create interactive maps for the web, that look and feel beautiful. This book will show you how build and design maps with D3.js and gives you great insight into projections, colors, and the most appropriate types of map. The book begins by helping you set up all the tools necessary to build visualizations and maps. Then it covers obtaining geographic data, modifying it to your specific needs, visualizing it with augmented data using D3.js. It will further show you how to draw and map with the Canvas API and how to publish your visualization. By the end of this book, you'll be creating maps like the election maps and the kind of infographics you'll find on sites like the New York Times.
Table of Contents (13 chapters)
6
Finding and Working with Geographic Data

Why Canvas interaction is different

In the preceding chapter, you achieved a smooth animation of thousands of points by doing away with the DOM. The DOM is a representation of each element in browser memory. Bypassing it, you were dealing with much less overhead during animation. However, the DOM can be very useful for other goals in web development. High up on that list – especially for data visualization – is the interaction with elements on screen.

You can just add an onmousemove or onclick listener to an element. You can’t do that to elements on a Canvas. They are a pixel manifestation of past code, not represented as a model within the browser.

However, don’t despair, there are indirect yet simple techniques to interact with your Canvas. We’ll be looking at the most important techniques in this chapter, building an interactive globe:

A...