added channels property

conversions.js

@@ -13,20 +13,33 @@ for (var key in cssKeywords) {
 }
 
 var convert = module.exports = {
-	rgb: {},
-	hsl: {},
-	hsv: {},
-	hwb: {},
-	cmyk: {},
-	xyz: {},
-	lab: {},
-	lch: {},
-	hex: {},
-	keyword: {},
-	ansi16: {},
-	ansi256: {}
+	rgb: {channels: 3},
+	hsl: {channels: 3},
+	hsv: {channels: 3},
+	hwb: {channels: 3},
+	cmyk: {channels: 4},
+	xyz: {channels: 3},
+	lab: {channels: 3},
+	lch: {channels: 3},
+	hex: {channels: 1},
+	keyword: {channels: 1},
+	ansi16: {channels: 1},
+	ansi256: {channels: 1}
 };
 
+// hide .channels property
+for (var model in convert) {
+	if (convert.hasOwnProperty(model)) {
+		if (!('channels' in convert[model])) {
+			throw new Error('missing channels property: ' + model);
+		}
+
+		var channels = convert[model].channels;
+		delete convert[model].channels;
+		Object.defineProperty(convert[model], 'channels', {value: channels});
+	}
+}
+
 convert.rgb.hsl = function (rgb) {
 	var r = rgb[0] / 255;
 	var g = rgb[1] / 255;

index.js

@@ -61,6 +61,8 @@ function wrapRounded(fn) {
 models.forEach(function (fromModel) {
 	convert[fromModel] = {};
 
+	Object.defineProperty(convert[fromModel], 'channels', {value: conversions[fromModel].channels});
+
 	var routes = route(fromModel);
 	var routeModels = Object.keys(routes);
 

test/basic.js

@@ -25,6 +25,10 @@ for (var len = models.length, i = 0; i < len; i++) {
 			console.log(chalk.red([fromModel, toModel].join('->')), chalk.red('(no conversion)'));
 		}
 	}
+
+	// should not expose channels
+	assert(convert[toModel].channels > 0);
+	assert(Object.keys(convert[toModel]).indexOf('channels') === -1);
 }
 
 assert.deepEqual(convert.rgb.hsl([140, 200, 100]), [96, 48, 59]);