Learning D3.js 5 Mapping - Second Edition

GeoJSON

GeoJSON is a specific JSON format for describing geographic data structures. It is important to know that GeoJSON does the following:

• Contains all the information required to draw geographic data.
• Is a standard JSON format and can be used instantly in JavaScript when building for the web.
• Is required by D3 when defining our d3.geoPath function, as seen in the previous chapters.
• Discretely defines each geographic shape. For example, if two countries share a border, the GeoJSON file will completely define both countries, therefore defining the border twice. It does not provide any mechanisms to optimize the data file.

Because D3 relies on GeoJSON, we will explain some of the highlights of the specification. For a complete explanation, ...