JS to create a sine-rainbow

sinebow.js

// Translated from code from Sam Kimbrel and Charlie Loyd
// via http://basecase.org/env/on-rainbows

const PHI = (1 + Math.pow(5, 0.5)) / 2;

function sinebow(hue) {
    // Choose a color from a sin^2-softened rainbow.
    var red = Math.pow(Math.cos(Math.PI * hue), 2) * 255;
    var green = Math.pow(Math.cos(Math.PI * (hue + 1/3)), 2) * 255;
    var blue = Math.pow(Math.cos(Math.PI * (hue + 2/3)), 2) * 255;
    return [Math.floor(red), Math.floor(green), Math.floor(blue)];
}

function choose_hex_color(n) {
    // Choose color number `n` from the sinebow using the angle of phi to reduce
    //  collision possibilities, and returning it as a hex-formatted color.
    var color = sinebow(n * PHI);
    return "#" + color.map(function (channel) {
        var hex = channel.toString(16);
        if (channel < 16) {
            hex = '0' + hex;
        }
        return hex;
    }).join('');
}

module.exports = {'sinebow': sinebow, 'choose_hex_color': choose_hex_color };