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

Experiment 3 – adding click events to our visualization

We've seen how to make a map and set different colors to the different regions of this map. Next, we will add a little bit of interactivity. This will illustrate a simple reference to bind click events to maps. For this experiment, we will build on the previous exercise, example-3.html. You can see the completed experiment at: http://localhost:8080/chapter-4/example-4.html.

First, we need a quick reference to each state in the country. To accomplish this, we will create a new function called geoID right below the mexico variable:

  var height = 600; 
  var width = 900; 
  var projection = d3.geoMercator(); 
  var mexico = void 0; 
 
  var geoID = function(d) { 
    return "c" + d.properties.ID_1; 
  }; 

This function takes in a state data element and generates a new selectable ID based on the ID_1 property...