server.js

/**
 * server.js
 * Copyright (c) 2015 marlun78
 * MIT License, https://gist.github.com/marlun78/bd0800cf5e8053ba9f83
 * Requires Node version >= 4.x
 */
'use strict';

const fs = require('fs');
const http = require('http');
const path = require('path');

const DEFAULT_FILE = process.env.DEFAULT_FILE || 'index.html';
const ROOT = process.env.ROOT || process.cwd();
const PORT = process.env.PORT || 9988;

const MIME_TYPE = {
    // Application
    JSON: 'application/json',
    // Image
    GIF: 'image/gif',
    ICO: 'image/ico',
    JPG: 'image/jpg',
    JPEG: 'image/jpeg',
    PNG: 'image/png',
    // Text
    CSS: 'text/css',
    HTML: 'text/html',
    JS: 'text/javascript',
    TXT: 'text/plain'
};

const NODE_ERROR = {
    NO_SUCH_FILE_OR_DIRECTORY: 'ENOENT'
};

const STATUS_CODE = {
    OK: 200,
    NOT_FOUND: 404,
    INTERNAL_SERVER_ERROR: 500
};

const STATUS_MESSAGE = {
    OK: '200 OK',
    NOT_FOUND: '404 Not Found',
    INTERNAL_SERVER_ERROR: '500 Internal Server Error'
};

const log = {
    writeln: console.log.bind(console)
};

const server = http.createServer(requestListener);
server.listen(PORT, listening);

function requestListener(request, response) {
    let absolutePath = resolveAbsolutePath(request.url);
    fs.readFile(absolutePath, (error, data) => {
        if (error) {
            handleError(response, error);
        } else {
            handleSuccess(response, absolutePath, data);
        }
    });
}

function resolveAbsolutePath(url) {
    let relativePath = url.replace(/\?.*/, '');
    if (relativePath.endsWith('/')) {
        relativePath += DEFAULT_FILE;
    }
    return path.join(ROOT, relativePath);
}

function handleSuccess(response, file, data) {
    log.writeln(STATUS_CODE.OK, file);
    response.writeHead(STATUS_CODE.OK, createHeaders(findMimeType(file)));
    response.end(data);
}

function handleError(response, error) {
    switch (error.code) {
        case NODE_ERROR.NO_SUCH_FILE_OR_DIRECTORY:
            log.writeln(STATUS_CODE.NOT_FOUND, error.toString());
            response.writeHead(STATUS_CODE.NOT_FOUND, createHeaders(MIME_TYPE.TXT));
            response.end(STATUS_MESSAGE.NOT_FOUND);
            break;
        default:
            log.writeln(STATUS_CODE.INTERNAL_SERVER_ERROR, error.toString());
            response.writeHead(STATUS_CODE.INTERNAL_SERVER_ERROR, createHeaders(MIME_TYPE.TXT));
            response.end(STATUS_MESSAGE.INTERNAL_SERVER_ERROR);
    }
}

function findMimeType(filePath) {
    let ext = path.extname(filePath).substr(1).toUpperCase();
    return MIME_TYPE[ext];
}

function listening() {
    console.log('Server started on', PORT);
}

function createHeaders(contentType) {
    return {
        'Content-Type': contentType
    };
}