chroma-js/src/io/hsl/hsl2rgb.js

JavaScript library for color conversions

import { unpack } from '../../utils/index.js';

const hsl2rgb = (...args) => {
    args = unpack(args, 'hsl');
    const [h, s, l] = args;
    let r, g, b;
    if (s === 0) {
        r = g = b = l * 255;
    } else {
        const t3 = [0, 0, 0];
        const c = [0, 0, 0];
        const t2 = l < 0.5 ? l * (1 + s) : l + s - l * s;
        const t1 = 2 * l - t2;
        const h_ = h / 360;
        t3[0] = h_ + 1 / 3;
        t3[1] = h_;
        t3[2] = h_ - 1 / 3;
        for (let i = 0; i < 3; i++) {
            if (t3[i] < 0) t3[i] += 1;
            if (t3[i] > 1) t3[i] -= 1;
            if (6 * t3[i] < 1) c[i] = t1 + (t2 - t1) * 6 * t3[i];
            else if (2 * t3[i] < 1) c[i] = t2;
            else if (3 * t3[i] < 2) c[i] = t1 + (t2 - t1) * (2 / 3 - t3[i]) * 6;
            else c[i] = t1;
        }
        [r, g, b] = [c[0] * 255, c[1] * 255, c[2] * 255];
    }
    if (args.length > 3) {
        // keep alpha channel
        return [r, g, b, args[3]];
    }
    return [r, g, b, 1];
};

export default hsl2rgb;