Javascript 从数组中的对象读取标签

Question

How to pass labels of data to.domain argument?

var data = {a: 9, b: 20, c:30, d:8, e:12, f:3, g:7, h:14}
 
var color = d3.scaleOrdinal()
  .domain(["a", "b", "c", "d", "e", "f", "g", "h"])
  .range(d3.schemeDark2);

So instead having .domain(["a", "b", "c", "d", "e", "f", "g", "h"]) I would like to have.domain(how to get labels from data variable?)

Answer 1

With Object.keys() you can get all names.

var data = {a: 9, b: 20, c:30, d:8, e:12, f:3, g:7, h:14}
var keys = Object.keys(data);

var color = d3.scaleOrdinal()
  .domain(keys)
  .range(d3.schemeDark2);