EventEmitter

• Interface
• Main methods:
  • on(event, handlerFunction)
  • emit(event, data)

ServerResponse

• Created by Server object
• Contains methods for response:
  • setHeader(key, val)
  • statusCode
  • write(data[, encoding])
  • and more...

node-core-apis/start/http-server-found.js

1. If user requests /found
   • HTTP status code: 200
   • respond with "you found it!"
2. Any other path
   • HTTP status code: 404
   • respond with "Not found! :("

Hints:

1. see table of contents on nodejs.org docs nodejs.org/dist/latest-v4.x/docs/api/http.html

• fs.read
• fs.open
• fs.link
• fs.write
• fs.chown
• fs.mkdir
• fs.stat
• etc.

⚠Synchronous versions⚠

• fs.readSync
• fs.openSync
• fs.linkSync
• fs.writeSync
• fs.chownSync
• fs.mkdirSync
• fs.statSync
• etc.

• fs.readFile(name[, options], cb)
• fs.writeFile(name, data[, options], cb)

function myCallback(err, userRecord){
  if(err) throw err;
  else console.log(userRecord);
}

db.getUser({ id : 30 }, myCallback);
console.log('db query queued');

function gotUser(err, user){ ... }
function writeComplete(err){ ... }
function parseHTML(err, response){ ... }

db.getUser({ id : 1 }, gotUser);
fs.writeFile('message.txt', "JS is Gr8!", 'utf8', writeComplete);
http.get('http://sequoia.makes.software', parseHTML);

Error First

var myCallback = function(err, ...

Always!!

Back to Filesystem

fs.writeFile

1. Write the string 'See you in San Francisco!' to letter.txt.
2. console.error on error
3. console.log success on success

Hints

1. RTFM (fs.writeFile)

Extra Credit:

1. If script is called with --apend, append instead of write

Up Next: Other Core Modules

URL

• url.parse(urlString)
• url.resolve(from,to)

querystring

• querystring.parse(queryStr)
• querystring.stringify(queryObject)

Process

• process.cwd()
• process.env
• process.argv
• process.exit(code)

node-core-apis/start/read-file-argv.js

1. Receive filename as argument
   node read-file.js someFile.txt
2. Read file
3. Write file contents to console
4. Ensure it works from another path (cd .. and run it again)

Hints:

1. Look around...

   console.log(process.argv);
   

2. File read path is relative to CWD

Globals

• __dirname
• __filename

Send HTML file

node-core-apis/start/read-file-server.js

1. Read index.html on any request
2. Send it back to the browser

Hints

1. fs, http, & path modules
2. Callbacks

Extra Credit

1. Allow port configuration with ENV variable
2. Stream from the filesystem to the browser

Up Next: NPM & the Node Ecosystem