serve.js

/*  
    This is a simple node server that will respond to requests on localhost.
    Call it from the command line with `node serve.js [port]`
    
    This script is intended for learning purposes. 
    A production system would require much more robust error handling.
    
    However, it serves to help us understand how node interoperates with http requests
    and file system resources.
    
    It will serve html, js and css files directly, and will render jade files to html.
    This naive implementation relies on the browser to parse the content-type of the 
    requested files ("text/css", "text/html", "image/jpeg", etc.).
*/

// Import node packages with the `require` function.
// This provides utility functions for http and filesystem resources
var http = require("http"),
  url = require("url"),
  path = require("path"),
  fs = require("fs"),
  // template engine: http://jade-lang.com
  jade = require('jade'),

  // Port can be set from the command line, or default to 8888
  port = process.argv[2] || 8888;

// Start the server. 
// The createServer() function takes a callback (receiving request and response objects)
// that will be executed on each request.
http.createServer(function(request, response) {
  
  // parse the request url to find the file that is being requested.
  var uri = url.parse(request.url).pathname,
    // the filename is built from the cwd (current working directory) of 
    // the current process, and the parsed uri path
    filename = path.join(process.cwd(), uri);
    
  // If the requested filename is a directory (eg, '/', the site root),
  // we will render and serve the 'index.jade' file from that directory
  if (fs.statSync(filename).isDirectory()) filename += '/index.jade';
    
  // fs.exists checks if the file exists
  // It will be deprecated and should be replaced with a call to fs.open
  // (http://nodejs.org/api/fs.html#fs_fs_exists_path_callback)
  fs.exists(filename, function(exists) {
    // however, in this case it makes it easy for us to return a 404 if the file isn't found
    if (!exists) {
      response.writeHead(404, {
        "Content-Type": "text/plain"
      });
      response.write("404 Not Found\n");
      response.end();
      return;
    }
    
    // Read the file in binary format. The callback receives any errors, and the file
    fs.readFile(filename, "binary", function(err, file) {
      // Respond to errors with Status code 500: "Internal server error"
      if (err) {
        response.writeHead(500, {
          "Content-Type": "text/plain"
        });
        response.write(err + "\n");
        response.end();
        return;
      }
      
      // Render the file through jade if file extension is .jade
      if (path.extname(filename) === '.jade') {
        // the `locals` var is passed to the template engine, for dynamic data
        // TODO: replace this with a calendar service
        var locals = {
          events: [{
            time: "Tuesday, February 24th: 6pm - 8pm",
            description: "NodeSchool Meetup - Hot Pink, Ink"
          }, {
            time: "Tuesday, March 10th: 6pm - 8pm",
            description: "HTML Preprocessor Workshop - Hot Pink, Ink"
          }]
        }
        // render the file
        file = jade.render(file, locals)
      }
      // And respond. Success!
      response.writeHead(200);
      response.write(file, "binary");
      response.end();
    });
  });
// The server won't start listening until we get to this part.
}).listen(parseInt(port, 10));

// Write to the console, to let the user know that it's runninng.
console.log("Static file server running at\n  => http://localhost:" + port + "/\nCTRL + C to shutdown");