Learn D3.js

Sorting

You can sort the objects (the leaves) inside each group using sortValues(). For example, this code will sort the movies by year (see Collections/6-nesting-sort.html):

const groupByDirector =     d3.nest()      .key(d => d.director)      .sortValues((a,b) => d3.ascending(a.year, b.year))      .entries(movies);

You can also sort by keys using sortKeys():

const groupByDirector =    d3.nest()      .key(d => d.director)      .sortKeys((a,b) => d3.ascending(a, b))      .sortValues((a,b) => d3.ascending(a.year, b.year))      .entries(movies);

Multiple key() methods can be called in order with different keys for multi-level nesting (see Collections/5-nesting-entries.html).