hexToHsl.js

/**
 * Convert #1a2b3c to { h: 210, g: 40, b: 17 }
 * @param {string} hex
 * @returns {*}
 * @see https://stackoverflow.com/q/46432335/3027390
 * @see https://stackoverflow.com/a/46432866/3027390
 */
function hexToHsl(hex) {
    const rgb = _f.hexToRgb(hex);
    const r = rgb.r / 255;
    const g = rgb.g / 255;
    const b = rgb.b / 255;
    const max = Math.max(r, g, b);
    const min = Math.min(r, g, b);
    let h;
    let s;
    let l = (max + min) / 2;

    if (max === min) {
        // Achromatic
        h = s = 0;
    } else {
        const delta = max - min;

        // Calculate hue
        switch (max) {
            case r:
                h = ((g - b) / delta) + ((g < b) ? 6 : 0);
                break;
            case g:
                h = ((b - r) / delta) + 2;
                break;
            case b:
                h = ((r - g) / delta) + 4;
                break;
        }

        h /= 6;

        // Calculate saturation
        if (l > 0.5) {
            s = delta / (2 - max - min);
        } else {
            s = delta / (max + min);
        }
    }

    h = Math.round(h * 360);
    s = Math.round(s * 100);
    l = Math.round(l * 100);

    return {
        h: h,
        s: s,
        l: l,
    };
}