contrastrast/esm/utils/contrastRatio.js

A lightweight tool that parses color strings and recommends text contrast based on WCAG Standards

import { Contrastrast } from "../contrastrast.js";
import { CONTRAST_RATIO } from "../constants.js";
/**
 * Calculate the WCAG 2.1 contrast ratio between two colors
 * @param color1 First color (Contrastrast instance or color string)
 * @param color2 Second color (Contrastrast instance or color string)
 * @returns Contrast ratio (1:1 to 21:1)
 */
export const contrastRatio = (color1, color2) => {
    const c1 = color1 instanceof Contrastrast ? color1 : new Contrastrast(color1);
    const c2 = color2 instanceof Contrastrast ? color2 : new Contrastrast(color2);
    const l1 = c1.luminance();
    const l2 = c2.luminance();
    const lighter = Math.max(l1, l2);
    const darker = Math.min(l1, l2);
    return (lighter + CONTRAST_RATIO.LUMINANCE_OFFSET) /
        (darker + CONTRAST_RATIO.LUMINANCE_OFFSET);
};