map color hues to same luminance

hues.lum.js

let lum = ([r, g, b]) => r * 0.2126 + g * 0.7152 + b * 0.0722;
let blend = (c0, c1, s, i = 1 - s) => [c0[0] * s + c1[0] * i, c0[1] * s + c1[1] * i, c0[2] * s + c1[2] * i];
let hex = c => c.reduce((p, v) => p + Math.round(0x100 + v * 0xff).toString(16).substr(-2), "");

let colors = {
    red:        [1, 0, 0],
    yellow:     [1, 1, 0],
    green:      [0, 1, 0],
    cyan:       [0, 1, 1],
    blue:       [0, 0, 1],
    magenta:    [1, 0, 1],
    white:      [1, 1, 1],
    black:      [0, 0, 0]
};

let t = 0.25;

Object.keys(colors).forEach(key => {
    let c = colors[key];
    let l = lum(c);
    let scaled;
    if (l > t) {
        scaled = blend(c, colors.black, t / l);
    } else {
        scaled = blend(colors.white, c, (t - l) / (1 - l));
    }
    console.log(key, scaled, hex(scaled), lum(scaled));
});