latest.js

var files = [
    'coquelux.01.08.01.tar.gz',
    'coquelux.01.08.09.tar.gz',
    'coquelux.01.08.100.tar.gz',
    'coquelux.01.08.10.tar.gz',
    'coquelux.01.08.99.tar.gz',
];

var getLatestVersion = function(files) {
    var latestVersion = [0, 0, 0];
    var latestVersionIndex = 0;
    var tarGzLen = '.tar.gz'.length;

    for (var i = 0; i < files.length; i++) {
        var version = files[i].slice(0, -tarGzLen).split('.').slice(-3).map(Number);
        for (j = 0; j < version.length; j++) {
            if (version[j] > latestVersion[j]) {
                latestVersion = version;
                latestVersionIndex = i;
                break;
            }
            if (version[j] < latestVersion[j]) {
                break;
            }
        }
    }

    return files[latestVersionIndex];
};

console.log(getLatestVersion(files));