normalize "degrees" and "radians" for deg2rad conversions

src/cubehelix.js

@@ -1,6 +1,6 @@
 import define, {extend} from "./define.js";
 import {Color, rgbConvert, Rgb, darker, brighter} from "./color.js";
-import {deg2rad, rad2deg} from "./math.js";
+import {degrees, radians} from "./math.js";
 
 var A = -0.14861,
     B = +1.78277,
@@ -21,7 +21,7 @@ function cubehelixConvert(o) {
       bl = b - l,
       k = (E * (g - l) - C * bl) / D,
       s = Math.sqrt(k * k + bl * bl) / (E * l * (1 - l)), // NaN if l=0 or l=1
-      h = s ? Math.atan2(k, bl) * rad2deg - 120 : NaN;
+      h = s ? Math.atan2(k, bl) * degrees - 120 : NaN;
   return new Cubehelix(h < 0 ? h + 360 : h, s, l, o.opacity);
 }
 
@@ -46,7 +46,7 @@ define(Cubehelix, cubehelix, extend(Color, {
     return new Cubehelix(this.h, this.s, this.l * k, this.opacity);
   },
   rgb: function() {
-    var h = isNaN(this.h) ? 0 : (this.h + 120) * deg2rad,
+    var h = isNaN(this.h) ? 0 : (this.h + 120) * radians,
         l = +this.l,
         a = isNaN(this.s) ? 0 : this.s * l * (1 - l),
         cosh = Math.cos(h),

src/lab.js

@@ -1,6 +1,6 @@
 import define, {extend} from "./define.js";
 import {Color, rgbConvert, Rgb} from "./color.js";
-import {deg2rad, rad2deg} from "./math.js";
+import {degrees, radians} from "./math.js";
 
 // https://observablehq.com/@mbostock/lab-and-rgb
 const K = 18,
@@ -85,7 +85,7 @@ function hclConvert(o) {
   if (o instanceof Hcl) return new Hcl(o.h, o.c, o.l, o.opacity);
   if (!(o instanceof Lab)) o = labConvert(o);
   if (o.a === 0 && o.b === 0) return new Hcl(NaN, 0 < o.l && o.l < 100 ? 0 : NaN, o.l, o.opacity);
-  var h = Math.atan2(o.b, o.a) * rad2deg;
+  var h = Math.atan2(o.b, o.a) * degrees;
   return new Hcl(h < 0 ? h + 360 : h, Math.sqrt(o.a * o.a + o.b * o.b), o.l, o.opacity);
 }
 
@@ -106,7 +106,7 @@ export function Hcl(h, c, l, opacity) {
 
 function hcl2lab(o) {
   if (isNaN(o.h)) return new Lab(o.l, 0, 0, o.opacity);
-  var h = o.h * deg2rad;
+  var h = o.h * radians;
   return new Lab(o.l, Math.cos(h) * o.c, Math.sin(h) * o.c, o.opacity);
 }
 

src/math.js

@@ -1,2 +1,2 @@
-export var deg2rad = Math.PI / 180;
-export var rad2deg = 180 / Math.PI;
+export const radians = Math.PI / 180;
+export const degrees = 180 / Math.PI;