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d3 v5.0 Release Notes

  • 🚀 Released March 22, 2018.

    🚀 This document covers only major changes. For minor and patch changes, please see the release notes.

    D3 5.0 introduces only a few non-backwards-compatible changes.

    👀 D3 now uses Promises instead of asynchronous callbacks to load data. Promises simplify the structure of asynchronous code, especially in modern browsers that support async and await. (See this introduction to promises on Observable.) For example, to load a CSV file in v4, you might say:

    d3.csv("file.csv", function(error, data) {
  if (error) throw error;
  console.log(data);
});

    In v5, using promises:

    d3.csv("file.csv").then(function(data) {
  console.log(data);
});

    Note that you don’t need to rethrow the error—the promise will reject automatically, and you can promise.catch if desired. Using await, the code is even simpler:

    const data = await d3.csv("file.csv");
console.log(data);

    🚚 With the adoption of promises, D3 now uses the Fetch API instead of XMLHttpRequest: the d3-request module has been replaced by d3-fetch. Fetch supports many powerful new features, such as streaming responses. D3 5.0 also deprecates and removes the d3-queue module. Use Promise.all to run a batch of asynchronous tasks in parallel, or a helper library such as p-queue to control concurrency.

    D3 no longer provides the d3.schemeCategory20* categorical color schemes. These twenty-color schemes were flawed because their grouped design could falsely imply relationships in the data: a shared hue can imply that the encoded data are part of a group (a super-category), while relative lightness can imply order. Instead, D3 now includes d3-scale-chromatic, which implements excellent schemes from ColorBrewer, including categorical, diverging, sequential single-hue and sequential multi-hue schemes. These schemes are available in both discrete and continuous variants.

    D3 now provides implementations of marching squares and density estimation via d3-contour! There are two new d3-selection methods: selection.clone for inserting clones of the selected nodes, and d3.create for creating detached elements. Geographic projections now support projection.angle, which has enabled several fantastic new polyhedral projections by Philippe Rivière.

    📦 Lastly, D3’s package.json no longer pins exact versions of the dependent D3 modules. This fixes an issue with duplicate installs of D3 modules.