d3-jsnext v3.5.5

d3-jsnext

d3, ported to ES6 modules.

Why?

Because most d3 projects only use a tiny fraction of d3's code. It has so much stuff in there - data manipulation, DOM stuff, AJAX, string interpolators, etc, etc... that you just don't need if you only want to (for example) generate a map projection function.

You can build d3 yourself, only including the bits that you need, but... can you really be bothered? And when you decide you want to use another d3 function that isn't in the build, do you waste time rebuilding it, or waste time implementing the function yourself?

ES6 modules allow you to selectively import the bits of a library that you actually need.

// Instead of this...
var d3 = require( 'd3' );
var projection = d3.geo.albers();

// ...write this:
import { albers } from 'd3-jsnext';
var projection = albers();

How does it work?

ES6 modules were designed from the ground for static analysis, which lets us determine which bits of a library you're using. (With CommonJS (i.e. node/browserify) and AMD modules, that just isn't possible.)

But you have to use the right tools. rollup is an ES6 module bundle that's smart enough to only include the right bits of code.

Does it really make that much difference?

Yes! Minified and gzipped, d3 weighs around 53kb. An adaptation of the Voronoi Tesselation example - you can see it here - weighs just 8kb, including the example code itself. Depending on which of d3's functions you're actually using, the savings can be even more dramatic.

How do I use it?

Check out the examples folder to see how to use d3-jsnext. You need to have a build step which takes your source code and bundles it up, but it can be as simple as typing a single command into your terminal. In theory, any ES6-aware module bundler will work, but for best results use rollup.

Note that whereas the examples use a relative path, in your own projects you should import from 'd3-jsnext'.

Table of import names

With regular d3, functions live in namespaces, like d3.geom.voronoi. ES6 modules don't work like that - instead, you import from a single namespace:

import { voronoi } from 'd3';
var layout = voronoi()...

In most cases, the import name is just the last part of the name as it was before. In a few cases (e.g d3.svg.line.radial and d3.svg.diagonal.radial) that introduces conflicts, so refer to the following table:

Building and testing

First, you need a local copy of d3's source code, plus its devDependencies:

npm run update-d3

Generating the ES6 modules and tests

npm run build

This will generate transformed tests and source code in the test and src folders respectively.

Running the tests

Err... the tests don't quite work yet. In progress! (It's tricky, because the test suite makes a number of perfectly justifiable assumptions that no longer hold.)

License etc

d3 is copyright Mike Bostock - license here.

d3-jsnext copyright Rich Harris and released under the MIT license.

Feedback

I'm @Rich_Harris on Twitter.