Fix #25 - prototype.constructor.

src/color.js

@@ -1,3 +1,5 @@
+import define, {extend} from "./define";
+
 export function Color() {}
 
 export var darker = 0.7;
@@ -163,14 +165,14 @@ var named = {
   yellowgreen: 0x9acd32
 };
 
-color.prototype = Color.prototype = {
+define(Color, color, {
   displayable: function() {
     return this.rgb().displayable();
   },
   toString: function() {
     return this.rgb() + "";
   }
-};
+});
 
 export default function color(format) {
   var m;
@@ -215,37 +217,33 @@ export function Rgb(r, g, b, opacity) {
   this.opacity = +opacity;
 }
 
-var _rgb = rgb.prototype = Rgb.prototype = new Color;
-
-_rgb.brighter = function(k) {
-  k = k == null ? brighter : Math.pow(brighter, k);
-  return new Rgb(this.r * k, this.g * k, this.b * k, this.opacity);
-};
-
-_rgb.darker = function(k) {
-  k = k == null ? darker : Math.pow(darker, k);
-  return new Rgb(this.r * k, this.g * k, this.b * k, this.opacity);
-};
-
-_rgb.rgb = function() {
-  return this;
-};
-
-_rgb.displayable = function() {
-  return (0 <= this.r && this.r <= 255)
-      && (0 <= this.g && this.g <= 255)
-      && (0 <= this.b && this.b <= 255)
-      && (0 <= this.opacity && this.opacity <= 1);
-};
-
-_rgb.toString = function() {
-  var a = this.opacity; a = isNaN(a) ? 1 : Math.max(0, Math.min(1, a));
-  return (a === 1 ? "rgb(" : "rgba(")
-      + Math.max(0, Math.min(255, Math.round(this.r) || 0)) + ", "
-      + Math.max(0, Math.min(255, Math.round(this.g) || 0)) + ", "
-      + Math.max(0, Math.min(255, Math.round(this.b) || 0))
-      + (a === 1 ? ")" : ", " + a + ")");
-};
+define(Rgb, rgb, extend(Color, {
+  brighter: function(k) {
+    k = k == null ? brighter : Math.pow(brighter, k);
+    return new Rgb(this.r * k, this.g * k, this.b * k, this.opacity);
+  },
+  darker: function(k) {
+    k = k == null ? darker : Math.pow(darker, k);
+    return new Rgb(this.r * k, this.g * k, this.b * k, this.opacity);
+  },
+  rgb: function() {
+    return this;
+  },
+  displayable: function() {
+    return (0 <= this.r && this.r <= 255)
+        && (0 <= this.g && this.g <= 255)
+        && (0 <= this.b && this.b <= 255)
+        && (0 <= this.opacity && this.opacity <= 1);
+  },
+  toString: function() {
+    var a = this.opacity; a = isNaN(a) ? 1 : Math.max(0, Math.min(1, a));
+    return (a === 1 ? "rgb(" : "rgba(")
+        + Math.max(0, Math.min(255, Math.round(this.r) || 0)) + ", "
+        + Math.max(0, Math.min(255, Math.round(this.g) || 0)) + ", "
+        + Math.max(0, Math.min(255, Math.round(this.b) || 0))
+        + (a === 1 ? ")" : ", " + a + ")");
+  }
+}));
 
 function hsla(h, s, l, a) {
   if (a <= 0) h = s = l = NaN;
@@ -291,37 +289,34 @@ function Hsl(h, s, l, opacity) {
   this.opacity = +opacity;
 }
 
-var _hsl = hsl.prototype = Hsl.prototype = new Color;
-
-_hsl.brighter = function(k) {
-  k = k == null ? brighter : Math.pow(brighter, k);
-  return new Hsl(this.h, this.s, this.l * k, this.opacity);
-};
-
-_hsl.darker = function(k) {
-  k = k == null ? darker : Math.pow(darker, k);
-  return new Hsl(this.h, this.s, this.l * k, this.opacity);
-};
-
-_hsl.rgb = function() {
-  var h = this.h % 360 + (this.h < 0) * 360,
-      s = isNaN(h) || isNaN(this.s) ? 0 : this.s,
-      l = this.l,
-      m2 = l + (l < 0.5 ? l : 1 - l) * s,
-      m1 = 2 * l - m2;
-  return new Rgb(
-    hsl2rgb(h >= 240 ? h - 240 : h + 120, m1, m2),
-    hsl2rgb(h, m1, m2),
-    hsl2rgb(h < 120 ? h + 240 : h - 120, m1, m2),
-    this.opacity
-  );
-};
-
-_hsl.displayable = function() {
-  return (0 <= this.s && this.s <= 1 || isNaN(this.s))
-      && (0 <= this.l && this.l <= 1)
-      && (0 <= this.opacity && this.opacity <= 1);
-};
+define(Hsl, hsl, extend(Color, {
+  brighter: function(k) {
+    k = k == null ? brighter : Math.pow(brighter, k);
+    return new Hsl(this.h, this.s, this.l * k, this.opacity);
+  },
+  darker: function(k) {
+    k = k == null ? darker : Math.pow(darker, k);
+    return new Hsl(this.h, this.s, this.l * k, this.opacity);
+  },
+  rgb: function() {
+    var h = this.h % 360 + (this.h < 0) * 360,
+        s = isNaN(h) || isNaN(this.s) ? 0 : this.s,
+        l = this.l,
+        m2 = l + (l < 0.5 ? l : 1 - l) * s,
+        m1 = 2 * l - m2;
+    return new Rgb(
+      hsl2rgb(h >= 240 ? h - 240 : h + 120, m1, m2),
+      hsl2rgb(h, m1, m2),
+      hsl2rgb(h < 120 ? h + 240 : h - 120, m1, m2),
+      this.opacity
+    );
+  },
+  displayable: function() {
+    return (0 <= this.s && this.s <= 1 || isNaN(this.s))
+        && (0 <= this.l && this.l <= 1)
+        && (0 <= this.opacity && this.opacity <= 1);
+  }
+}));
 
 /* From FvD 13.37, CSS Color Module Level 3 */
 function hsl2rgb(h, m1, m2) {

src/cubehelix.js

@@ -1,3 +1,4 @@
+import define, {extend} from "./define";
 import {Color, rgbConvert, Rgb, darker, brighter} from "./color";
 import {deg2rad, rad2deg} from "./math";
 
@@ -35,28 +36,26 @@ export function Cubehelix(h, s, l, opacity) {
   this.opacity = +opacity;
 }
 
-var _cubehelix = cubehelix.prototype = Cubehelix.prototype = new Color;
-
-_cubehelix.brighter = function(k) {
-  k = k == null ? brighter : Math.pow(brighter, k);
-  return new Cubehelix(this.h, this.s, this.l * k, this.opacity);
-};
-
-_cubehelix.darker = function(k) {
-  k = k == null ? darker : Math.pow(darker, k);
-  return new Cubehelix(this.h, this.s, this.l * k, this.opacity);
-};
-
-_cubehelix.rgb = function() {
-  var h = isNaN(this.h) ? 0 : (this.h + 120) * deg2rad,
-      l = +this.l,
-      a = isNaN(this.s) ? 0 : this.s * l * (1 - l),
-      cosh = Math.cos(h),
-      sinh = Math.sin(h);
-  return new Rgb(
-    255 * (l + a * (A * cosh + B * sinh)),
-    255 * (l + a * (C * cosh + D * sinh)),
-    255 * (l + a * (E * cosh)),
-    this.opacity
-  );
-};
+define(Cubehelix, cubehelix, extend(Color, {
+  brighter: function(k) {
+    k = k == null ? brighter : Math.pow(brighter, k);
+    return new Cubehelix(this.h, this.s, this.l * k, this.opacity);
+  },
+  darker: function(k) {
+    k = k == null ? darker : Math.pow(darker, k);
+    return new Cubehelix(this.h, this.s, this.l * k, this.opacity);
+  },
+  rgb: function() {
+    var h = isNaN(this.h) ? 0 : (this.h + 120) * deg2rad,
+        l = +this.l,
+        a = isNaN(this.s) ? 0 : this.s * l * (1 - l),
+        cosh = Math.cos(h),
+        sinh = Math.sin(h);
+    return new Rgb(
+      255 * (l + a * (A * cosh + B * sinh)),
+      255 * (l + a * (C * cosh + D * sinh)),
+      255 * (l + a * (E * cosh)),
+      this.opacity
+    );
+  }
+}));

src/define.js

@@ -0,0 +1,10 @@
+export default function(constructor, factory, prototype) {
+  constructor.prototype = factory.prototype = prototype;
+  prototype.constructor = constructor;
+}
+
+export function extend(parent, definition) {
+  var prototype = Object.create(parent.prototype);
+  for (var key in definition) prototype[key] = definition[key];
+  return prototype;
+}

src/lab.js

@@ -1,3 +1,4 @@
+import define, {extend} from "./define";
 import {Color, rgbConvert, Rgb} from "./color";
 import {deg2rad, rad2deg} from "./math";
 
@@ -37,30 +38,28 @@ export function Lab(l, a, b, opacity) {
   this.opacity = +opacity;
 }
 
-var _lab = lab.prototype = Lab.prototype = new Color;
-
-_lab.brighter = function(k) {
-  return new Lab(this.l + Kn * (k == null ? 1 : k), this.a, this.b, this.opacity);
-};
-
-_lab.darker = function(k) {
-  return new Lab(this.l - Kn * (k == null ? 1 : k), this.a, this.b, this.opacity);
-};
-
-_lab.rgb = function() {
-  var y = (this.l + 16) / 116,
-      x = isNaN(this.a) ? y : y + this.a / 500,
-      z = isNaN(this.b) ? y : y - this.b / 200;
-  y = Yn * lab2xyz(y);
-  x = Xn * lab2xyz(x);
-  z = Zn * lab2xyz(z);
-  return new Rgb(
-    xyz2rgb( 3.2404542 * x - 1.5371385 * y - 0.4985314 * z), // D65 -> sRGB
-    xyz2rgb(-0.9692660 * x + 1.8760108 * y + 0.0415560 * z),
-    xyz2rgb( 0.0556434 * x - 0.2040259 * y + 1.0572252 * z),
-    this.opacity
-  );
-};
+define(Lab, lab, extend(Color, {
+  brighter: function(k) {
+    return new Lab(this.l + Kn * (k == null ? 1 : k), this.a, this.b, this.opacity);
+  },
+  darker: function(k) {
+    return new Lab(this.l - Kn * (k == null ? 1 : k), this.a, this.b, this.opacity);
+  },
+  rgb: function() {
+    var y = (this.l + 16) / 116,
+        x = isNaN(this.a) ? y : y + this.a / 500,
+        z = isNaN(this.b) ? y : y - this.b / 200;
+    y = Yn * lab2xyz(y);
+    x = Xn * lab2xyz(x);
+    z = Zn * lab2xyz(z);
+    return new Rgb(
+      xyz2rgb( 3.2404542 * x - 1.5371385 * y - 0.4985314 * z), // D65 -> sRGB
+      xyz2rgb(-0.9692660 * x + 1.8760108 * y + 0.0415560 * z),
+      xyz2rgb( 0.0556434 * x - 0.2040259 * y + 1.0572252 * z),
+      this.opacity
+    );
+  }
+}));
 
 function xyz2lab(t) {
   return t > t3 ? Math.pow(t, 1 / 3) : t / t2 + t0;
@@ -96,16 +95,14 @@ export function Hcl(h, c, l, opacity) {
   this.opacity = +opacity;
 }
 
-var _hcl = hcl.prototype = Hcl.prototype = new Color;
-
-_hcl.brighter = function(k) {
-  return new Hcl(this.h, this.c, this.l + Kn * (k == null ? 1 : k), this.opacity);
-};
-
-_hcl.darker = function(k) {
-  return new Hcl(this.h, this.c, this.l - Kn * (k == null ? 1 : k), this.opacity);
-};
-
-_hcl.rgb = function() {
-  return labConvert(this).rgb();
-};
+define(Hcl, hcl, extend(Color, {
+  brighter: function(k) {
+    return new Hcl(this.h, this.c, this.l + Kn * (k == null ? 1 : k), this.opacity);
+  },
+  darker: function(k) {
+    return new Hcl(this.h, this.c, this.l - Kn * (k == null ? 1 : k), this.opacity);
+  },
+  rgb: function() {
+    return labConvert(this).rgb();
+  }
+}));

test/cubehelix-test.js

@@ -0,0 +1,10 @@
+var tape = require("tape"),
+    color = require("../");
+
+tape("cubehelix(…) returns an instance of cubehelix and color", function(test) {
+  var c = color.cubehelix("steelblue");
+  test.ok(c instanceof color.cubehelix);
+  test.ok(c instanceof color.color);
+  test.equal(c.constructor.name, "Cubehelix");
+  test.end();
+});

test/hcl-test.js

@@ -8,6 +8,7 @@ tape("hcl(…) returns an instance of hcl and color", function(test) {
   var c = color.hcl(120, 40, 50);
   test.ok(c instanceof color.hcl);
   test.ok(c instanceof color.color);
+  test.equal(c.constructor.name, "Hcl");
   test.end();
 });
 

test/hsl-test.js

@@ -8,6 +8,7 @@ tape("hsl(…) returns an instance of hsl and color", function(test) {
   var c = color.hsl(120, 0.4, 0.5);
   test.ok(c instanceof color.hsl);
   test.ok(c instanceof color.color);
+  test.equal(c.constructor.name, "Hsl");
   test.end();
 });
 

test/lab-test.js

@@ -8,6 +8,7 @@ tape("lab(…) returns an instance of lab and color", function(test) {
   var c = color.lab(120, 40, 50);
   test.ok(c instanceof color.lab);
   test.ok(c instanceof color.color);
+  test.equal(c.constructor.name, "Lab");
   test.end();
 });
 

test/rgb-test.js

@@ -7,6 +7,7 @@ tape("rgb(…) returns an instance of rgb and color", function(test) {
   var c = color.rgb(70, 130, 180);
   test.ok(c instanceof color.rgb);
   test.ok(c instanceof color.color);
+  test.equal(c.constructor.name, "Rgb");
   test.end();
 });