Automated changing flat stripe background for ghost.

ghost-seasons-background.js

(function(){
    //SVG Flat Stripe Background
    //by Khinenw
    //gist.github.com/HelloWorld017/6fb557767095a0e79140cb3bfbed83e7
    'use strict';

    if(location.pathname !== '/') return;

    var themes = [[/^\d+-(02|03|04)-.+$/, ['#f8bbd0', '#f06292', '#e91e63', '#c2185b', '#880e4f']], //Haru
    [/^\d+-(05|06|07)-.+$/, ['#ffeb3b', '#cddc39', '#8bc34a', '#4caf50', '#009688']], //Natsu
    [/^\d+-(08|09|10)-.+$/, ['#ff9800', '#fb8c00', '#f57c00', '#ef6c00', '#e65100']], //Aki
    [/^\d+-(11|12|01)-.+$/, ['#e1f5fe', '#4fc3f7', '#03a9f4', '#0288d1', '#01579b']] //Fuyu
    ];

    var fullHeight = 2048;
    var fullWidth = 2048;
    var stripeCount = 5;
    var stripeUnit = fullHeight / stripeCount;
    var stripeWidth = 64;
    var stripeMinHeight = stripeUnit / 4;
    var stripeMaxHeight = stripeUnit / 1.5;
    var stripeRadius = 32;
    var stripeColors = themes.find(function (v) {
        return v[0].test(new Date().toISOString());
    })[1];

    var path = [];
    var buildPath = function buildPath(color) {
        for (var _len = arguments.length, args = Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
            args[_key - 1] = arguments[_key];
        }

        return '<path fill="' + color + '" d="' + args.map(function (v) {
            return v.shift() + ' ' + v.join(',');
        }).join(' ') + '"/>';
    };

    for (var i = 0; i < stripeCount; i++) {
        var y = i * stripeUnit;
        path.push(buildPath(stripeColors[i], ['M', 0, y], ['L', fullWidth, y], ['L', fullWidth, y + stripeUnit], ['L', 0, y + stripeUnit], ['Z']));

        var j = 0;
        for (var x = 0; x < fullWidth; x += stripeWidth) {
            var randomHeight = Math.floor(Math.random() * (stripeMaxHeight - stripeMinHeight)) + stripeMinHeight;

            path.push(buildPath(i === 0 || j % 2 === 0 ? stripeColors[i] : stripeColors[i - 1], ['M', x, y - (randomHeight / 2 - stripeRadius)], ['A',
            //x + fullWidth / 2,
            //y - (randomHeight / 2 - stripeRadius),
            stripeRadius, stripeRadius, 0, 0, 1, x + stripeWidth, y - (randomHeight / 2 - stripeRadius)], ['L', x + stripeWidth, y + (randomHeight / 2 - stripeRadius)], ['A',
            //x + fullWidth / 2,
            //y + (randomHeight / 2 - stripeRadius),
            stripeRadius, stripeRadius, 0, 0, 1, x, y + (randomHeight / 2 - stripeRadius)], ['Z']));
            j++;
        }
    }

    var svgString = "url('data:image/svg+xml;base64," + btoa('<svg width="' + fullWidth + '" height="' + fullHeight + '" xmlns="http://www.w3.org/2000/svg">' + path.join('\n') + '</svg>') + "')";

    var $ = document.querySelector.bind(document);
    var header = $('.main-header');
    header.classList.remove('no-cover');
    header.style.background = svgString;
    jarallax(header, {
        speed: 0.5
    });
})();