RGB转HSL，HSL转RGB

其中的逻辑没搞懂，以下方法绝大部分颜色转换没问题，有问题的一般都是某个色值会相差一点，视觉上看不出来。

RGB转HSL，参数取值[0,255]，返回值除第一个，都是百分值

function rgbToHsl(r, g, b) {
    r /= 255, g /= 255, b /= 255;
    var max = Math.max(r, g, b),
        min = Math.min(r, g, b);
    var h, s, l = (max + min) / 2;

    if (max == min) {
        h = s = 0;
    } else {
        var d = max - min;
        s = l > 0.5 ? d / (2 - max - min) : d / (max + min);
        switch (max) {
            case r:
                h = (g - b) / d + (g < b ? 6 : 0);
                break;
            case g:
                h = (b - r) / d + 2;
                break;
            case b:
                h = (r - g) / d + 4;
                break;
        }
        h /= 6;
    }

    return [h * 360, s * 100, l * 100];
}
console.log(rgbToHsl(250, 110, 200))

HSL转RGB，参数取值，第一个[0,360]，二三[0,1]

function hslToRgb(h, s, l) {
    h = h / 360;
    var r, g, b;

    if (s == 0) {
        r = g = b = l;
    } else {
        function hue2rgb(p, q, t) {
            if (t < 0) t += 1;
            if (t > 1) t -= 1;
            if (t < 1 / 6) return p + (q - p) * 6 * t;
            if (t < 1 / 2) return q;
            if (t < 2 / 3) return p + (q - p) * (2 / 3 - t) * 6;
            return p;
        }

        var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
        var p = 2 * l - q;
        r = hue2rgb(p, q, h + 1 / 3);
        g = hue2rgb(p, q, h);
        b = hue2rgb(p, q, h - 1 / 3);
    }

    return [Math.round(r * 255), Math.round(g * 255), Math.round(b * 255)];
}
console.log(hslToRgb(240, 1, 0.5))

var hslToRgb = function(hue, saturation, lightness) {
    if (hue == undefined) {
        return [0, 0, 0];
    }

    var chroma = (1 - Math.abs((2 * lightness) - 1)) * saturation;
    var huePrime = hue / 60;
    var secondComponent = chroma * (1 - Math.abs((huePrime % 2) - 1));

    huePrime = Math.floor(huePrime);
    var red;
    var green;
    var blue;

    if (huePrime === 0 || huePrime === 6) {
        red = chroma;
        green = secondComponent;
        blue = 0;
    } else if (huePrime === 1) {
        red = secondComponent;
        green = chroma;
        blue = 0;
    } else if (huePrime === 2) {
        red = 0;
        green = chroma;
        blue = secondComponent;
    } else if (huePrime === 3) {
        red = 0;
        green = secondComponent;
        blue = chroma;
    } else if (huePrime === 4) {
        red = secondComponent;
        green = 0;
        blue = chroma;
    } else if (huePrime === 5) {
        red = chroma;
        green = 0;
        blue = secondComponent;
    }

    var lightnessAdjustment = lightness - (chroma / 2);
    red += lightnessAdjustment;
    green += lightnessAdjustment;
    blue += lightnessAdjustment;

    return [Math.round(red * 255), Math.round(green * 255), Math.round(blue * 255)];

}
console.log(hslToRgb(240, 1, 0.5))