cheatsheets/nodejs.md

title	layout
Node.js API	default

Globals

__filename
__dirname

fs

Reading

fs.readFile('file.txt', function(err, data) { .. });
fs.readFile('file.txt', {encoding: 'utf-8'}, function(err, data) { .. });

Writing

fs.writeFile('output.txt', function(err) { .. });
fs.appendFile('output.txt', function(err) { .. });

Watch

fs.watch('dir OR file.txt', { persistent: true }, function(event, file) {
  event; /* rename | change */
});

Getting info

fs.exists('file.txt', function(exists /*bool*/) { ... });

fs.stat('file.txt', function(stats) {
  stats.isFile();
  stats.isDirectory();
  stats.isSymbolicLink();
});

File operations

fs.rename('old.txt', 'new.txt', function(){});
fs.chown('file.txt', uid, gid, function(){});
fs.symlink('src', 'dest', function(){});
fs.unlink('path', function(){});
fs.rmdir('path', function(){});

fs.readdir('path', function(err, files) { .. }); /* `files` = array of names */

Path

fs.realpath('/etc/passwd', function(err, path) { /* "/private/etc/passwd" */ });

Sync

data = fs.readFileSync('input.txt');
fs.writeFileSync('output.txt', data);
fs.appendFileSync('output.txt', data);
fs.existsSync('file.txt');

process

Streams

process.stdout.write('...');
process.stderr.write('...');

function stdin(fn) {
  var data = '';

  process.stdin.setEncoding('utf8');
  process.stdin.on('readable', function() {
    var chunk = process.stdin.read();
    if (chunk !== null) data += chunk;
  });

  process.stdin.on('end', function() {
    fn(null, data);
  });
}

stuff

process.argv; //=> ['node', 'file.js', 'one', 'two']
process.env; //=> {TERM: 'screen-256color', SHELL: '/bin/bash', ...}

process.exit();
process.exit(1);

Directories

process.cwd(); //=> "/tmp"
process.chdir('dir');

path

fs.realpath('/etc/passwd', function(err, path) { /* "/private/etc/passwd" */ });

dir = path.join('etc', 'passwd');
dir = path.resolve('/etc', 'passwd', '..', 'var');

path.dirname('/etc/passwd')       //=> "/etc"
path.basename('/etc/passwd')      //=> "passwd"
path.basename('/etc/rc.d', '.d')  //=> "rc"

exec

var exec = require('child_process').exec,

var child = exec('cat *.js bad_file | wc -l',
  function (error, stdout, stderr) {
    console.log('stdout: ' + stdout);
    console.log('stderr: ' + stderr);
    if (error !== null) {
      console.log('exec error: ' + error);
    }
});

assert

assert(val)
assert.equal(actual, expected)
assert.notEqual(a, e)

assert.deepEqual(a, e)
assert.notDeepEqual(a, e)

assert.throws(fn)

Snippets

info = require('../package.json')
info.version

process.stdout.write(util.inspect(objekt, false, Infinity, true) + '\n');

Spawn - passthru the in/out

var spawn = require('child_process').spawn;
var proc = spawn(bin, argv, { stdio: 'inherit' });
proc.on('error', function(err) {
  if (err.code == "ENOENT") { "does not exist" }
  if (err.code == "EACCES") { "not executable" }
});
proc.on('exit', function(code) { ... });

// also { stdio: ['pipe', 'pipe', process.stdout] }
// also { stdio: [process.stdin, process.stderr, process.stdout] }

proc.stdout.on('data', function (data) {
});
proc.stderr.on('data', function (data) {
});