chore: Refactor repeated code (#110)

.changeset/strong-numbers-grab.md

@@ -0,0 +1,5 @@
+---
+"@sardine/colour": patch
+---
+
+Optimise bundle size by refactoring repeated code. Saved 0.02 kB

src/getContrastRatioFromCSSRGB.ts

@@ -1,6 +1,7 @@
 import { convertCSSRGBtoRGB } from "./convertCSSRGBtoRGB";
 import { getSRGBLuminanceFromRGB } from "./getSRGBLuminanceFromRGB";
 import type { WCAG } from "./types";
+import { calculateContrastRatio } from "./util/calculateContrastRatio";
 
 /**
  * Calculates the contrast ratio between two colours in CSSRGB format.
@@ -20,15 +21,5 @@ export function getContrastRatioFromCSSRGB(
 	const luminance1 = getSRGBLuminanceFromRGB(rgbColour1, standard);
 	const luminance2 = getSRGBLuminanceFromRGB(rgbColour2, standard);
 
-	// Determine which colour is lighter and which is darker
-	const lighter = Math.max(luminance1, luminance2);
-	const darker = Math.min(luminance1, luminance2);
-
-	// Calculate the contrast ratio
-	// The spec sets the ratio as (L1 + 0.05) / (L2 + 0.05) where L1 is the lighter colour and L2 is the darker colour
-	// https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html
-	const ratio = (lighter + 0.05) / (darker + 0.05);
-
-	// Return the contrast ratio truncated to 3 decimal places
-	return Math.floor(ratio * 1000) / 1000;
+	return calculateContrastRatio(luminance1, luminance2);
 }

src/getContrastRatioFromHex.ts

@@ -1,5 +1,6 @@
 import { getSRGBLuminanceFromHex } from "./getSRGBLuminanceFromHex";
 import type { WCAG } from "./types";
+import { calculateContrastRatio } from "./util/calculateContrastRatio";
 
 /**
  * Calculates the contrast ratio between two colours in hexadecimal format.
@@ -17,15 +18,5 @@ export function getContrastRatioFromHex(
 	const luminance1 = getSRGBLuminanceFromHex(colour1, standard);
 	const luminance2 = getSRGBLuminanceFromHex(colour2, standard);
 
-	// Determine which colour is lighter and which is darker
-	const lighter = Math.max(luminance1, luminance2);
-	const darker = Math.min(luminance1, luminance2);
-
-	// Calculate the contrast ratio
-	// The spec sets the ratio as (L1 + 0.05) / (L2 + 0.05) where L1 is the lighter colour and L2 is the darker colour
-	// https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html
-	const ratio = (lighter + 0.05) / (darker + 0.05);
-
-	// Return the contrast ratio truncated to 3 decimal places
-	return Math.floor(ratio * 1000) / 1000;
+	return calculateContrastRatio(luminance1, luminance2);
 }

src/util/calculateContrastRatio.test.ts

@@ -0,0 +1,8 @@
+import { expect, it } from "vitest";
+import { calculateContrastRatio } from "./calculateContrastRatio";
+
+it("should calculate the contrast ratio between two luminances", () => {
+	expect(calculateContrastRatio(0.05780543019106723, 0.16288822420427432)).toBe(
+		1.974,
+	);
+});

src/util/calculateContrastRatio.ts

@@ -0,0 +1,22 @@
+/**
+ * Calculate the contrast ratio between two colours
+ * @param luminance1 The luminance of the first colour
+ * @param luminance2 The luminance of the second colour
+ * @returns The contrast ratio between the two colours truncated to 3 decimal places
+ */
+export function calculateContrastRatio(
+	luminance1: number,
+	luminance2: number,
+): number {
+	// Determine which colour is lighter and which is darker
+	const lighter = Math.max(luminance1, luminance2);
+	const darker = Math.min(luminance1, luminance2);
+
+	// Calculate the contrast ratio
+	// The spec sets the ratio as (L1 + 0.05) / (L2 + 0.05) where L1 is the lighter colour and L2 is the darker colour
+	// https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html
+	const ratio = (lighter + 0.05) / (darker + 0.05);
+
+	// Return the contrast ratio truncated to 3 decimal places
+	return Math.floor(ratio * 1000) / 1000;
+}