Learn D3.js

Loading external files

Usually, your data will come from external files that need to be loaded with an Ajax request. You can, of course, use jQuery or ECMAScript fetch() commands (and promises, if you need to load multiple files). After loading, you will also need to parse the data and convert it into JavaScript arrays and objects. D3 again provides a more efficient solution in the d3-fetch module: a set of convenient methods for loading and parsing files in popular formats, such as XML, JSON, or CSV. The d3-fetch module is also included in the default bundle.

The planetary data we used in the previous examples is actually part of a larger JSON file containing several properties for planets, asteroids, and satellites. The basic structure ...