node.js Module Development

M O D U L E D E V E L O P M E N T

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Node.js is a platform built on
Chrome's JavaScript runtime for
easily building fast, scalable network
applications.
“
”
What is node.js?

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./

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sourceControl
git init

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javascriptFiles
mkdir ./lib

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executableFiles
mkdir ./bin

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testFiles
mkdir ./test

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documentationFiles
mkdir ./doc
mkdir ./example
mkdir ./man

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informationalFiles
touch ./README
touch ./LICENSE
touch ./AUTHOR

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./bin
./doc
./example
./lib
./man
./test
singularNouns

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packageManagement

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Package Manager

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github:
install:
isaacs/npm
comes with node

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npm install
localInstallation

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npm install --global
globalInstallation
-g or --global

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npm install --link
dualInstallation

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npm install --save[-dev]
dependencyReferences
--save or --save-dev

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npm install
updateDependencies

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npm init
packageInitialization

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$ npm init
name: (sample-node) Sample
version: (0.0.0) 0.1.0
description: This is a sample module
entry point: (index.js) _

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author: Jay Harris
license: (BSD) BSD
About to write to /Projects/sample-‐node/package.json:
{
"name": "Sample",
"version": "0.1.0",
"description": "This is a sample module",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "Jay Harris",
"license": "BSD"
}
Is this ok? (yes) _

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./package.json
{
"name": "Sample",
"version": "0.1.0",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no tests avail.\" && exit 1"
},
"license": "BSD"
}
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npm init is additive not destructive

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moduleCreation

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module

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module.exports

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./lib/sample.js
module.exports.sayHello = function() {
return "Hello World!";
}
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var sample = require("./lib/sample.js");
// Returns 'Hello World!'
sample.sayHello();

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./lib/person.js
function Person(first, last) {
if (!(this instanceof Person)) {
return new Person(first, last);
}
this.firstName = first;
this.lastName = last;
return this;
}
module.exports = Person;
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var person = require("./lib/person.js");
// This will return undefined
person.firstName;
// This will return 'Jay'
var jayHarris = new Person('Jay','Harris');
jayHarris.firstName;

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// ...
}
// This is a public method;
Person.prototype.sayHello = function() {
return _join.call(this, "Hello", this.firstName);
}
// This is a private method
var _join(first, second) {
return first + ' ' + second;
}
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// This will throw 'Has No Method' error
person.sayHello();
// This will return 'Hello Jay'
jayHarris.sayHello();

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// ...
}
// This is a static method
module.exports.sayHello = function() {
return "Hello World!";
}
// This is a public instance method;
Person.prototype.sayHello = function() {
return _join.call(this, "Hello", this.firstName);
}
// This is a private method
var _join(first, second) {
return first + ' ' + second;
}
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// This will return 'Hello World!'
person.sayHello();
jayHarris.sayHello();

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eventEmitter

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var EventEmitter = require('events').EventEmitter;

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EventEmitter.call(this);

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var util = require('util');
// ...
util.inherits(MyClass, EventEmitter);

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var EventEmitter = require('events').EventEmitter
, util = require('util');
// ...
EventEmitter.call(this);
// ...
}
util.inherits(Person, EventEmitter);
Person.prototype.goToBed = function() {
this.emit("sleep");
}
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var person = require("./person.js");
jayHarris.on("sleep", function() {
console.log("Goodnight, Jay");
}
jayHarris.goToBed();
// Output 'Goodnight, Jay'

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testingNode.js

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TDD is to coding style as yoga is
to posture. Even when you're not
actively practicing, having done so
colors your whole life healthier.”
j. kerr
“

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assertingCorrectness

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var assert = require('assert');

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assert(value)
.ok(value)
.equal(actual, expected)
.notEqual(actual, expected)
.deepEqual(actual, expected)
.notDeepEqual(actual, expected)
.strictEqual(actual, expected)
.notStrictEqual(actual, expected)
.throws(block, [error])
.doesNotThrow(block, [error])
.ifError(value)

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// Will pass
assert.ok(true);
// Will throw an exception
assert.ok(false);
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// Will throw 'false == true' error
assert.ok(typeof 'hello' === 'number');
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$ node test.js
assert.js:104
throw new assert.AssertionError({
^
AssertionError: false == true
at Object. (my-‐test.js:7:8)
at Module._compile (module.js:449:26)
at Object.Module._extensions..js (module.js:467:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Module.runMain (module.js:487:10)
at process.startup.processNextTick.process._tick...
$ _

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Chai Assertion Library

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github:
install:
chaijs/chai
npm install chai

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isTrue, isFalse,
isNull, isNotNull,
isUndefined, isDefined,
isFunction, isNotFunction,
isArray, isNotArray,
isBoolean, isNotBoolean,
isNumber, isNotNumber,
isString, isNotString,
include,
lengthOf,
operator,
closeTo
isObject, isNotObject,
typeOf, notTypeOf,
instanceOf, notInstanceOf,
match, notMatch,
property, notProperty,
deepProperty, notDeepProperty,
propertyVal, propertyNotVal,
deepPropertyVal, deepPropertyNotVal,
additional
assertions

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var assert = require('chai').assert;

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// Will throw 'expected 'hello' to be a number'
assert.isNumber('hello');
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$ node test.js
expected 'hello' to be a number
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var chai = require('chai')
, assert = chai.assert;
chai.Assertion.includeStack = true;
// Will throw and display stack
assert.isNumber('hello');
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expectAssertions

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expectSyntax
expect(person).to.be.an('object');
.with.property('age')
.that.is.a('number')
.that.equals(34);
assert.isObject(person);
assert.property(person, "age");
assert.isNumber(person.age);
assert.equals(person.age, 34);
assertSyntax

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var expect = require('chai').expect;

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assertionChains
for readability

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expect(person).to.exist
.and.be.an('object')
.that.is.to.exist
.and.is.a('number')
.and.equals(34);

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.to
.be
.been
.is
.that
.and
.have
.with
syntaxSugar
for readability

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expect(person).to.exist
.and.be.an('object')
.that.is.to.exist
.and.is.a('number')
.and.equals(34);

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.property
subjectChange
from original object

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expect(person)
.that.is.an('object')
.with.property('address')
.that.is.an('object')
.with.property('city')
.that.is.a('string')
.and.equals('Detroit')

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testingFramework

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mocha simple, flexible, fun

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mocha
github:
install:
visionmedia/mocha
npm install -g mocha

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$ npm install -‐g mocha
$ mkdir test
$ mocha

✔ 0 tests complete (1ms)
$

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var mocha = require('mocha');

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describe('Testing out this thing', function() {
it('should do stuff', function() {
// Assertion tests
});
});
bddSyntax

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./test/my-test.js
describe('Assertions', function() {
it('should pass on truthiness', function() {
assert.ok(true);
});
it('should fail on falsiness', function() {
assert.ok(false);
});
});
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$ mocha -‐-‐reporter spec
Assertions
✓ should pass on truthiness
1) should fail on falsiness
✖ 1 of 2 tests failed:
1) Assertions should fail on falsiness:

at (stack trace omitted for brevity)
$ _

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groupedTests

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describe('with a subset of this other thing', function() {
// Assertion tests
});
});
});
groupSyntax

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Assertions
of equality
✓ should pass on falsiness
on type
✓ should pass on number
$ _

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pendingTests

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describe('with a subset of this other thing', function() {
it('should do stuff someday');
});
});
pendingSyntax

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describe('of truthiness', function() {
expect(true).is.true;
});
expect(false).is.false;
});
});
describe('of type', function() {
it('should pass on number', function() {
expect(5).is.a('number');
});
it('should pass on object');
});
});
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Assertions
of truthiness
of type
✓ should pass on number
-‐ should pass on object
• 1 test pending
$ _

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skippedTests

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it.skip('should be skipped', function() {
// Assertion tests
});
});
describe.skip('This entire suite will be skipped', function() {
// Assertion tests
});
});
skipSyntax

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describe('of truthiness', function() {
assert.isTrue(true);
});
assert.isFalse(false);
});
});
describe('of type', function() {
it.skip('should pass on number', function() {
assert.isNumber(5);
});
it('should pass on object');
});
});
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$ make test
Assertions
of truthiness
of type
-‐ should pass on number
-‐ should pass on object
• 2 test pending
$ _

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setupTeardown

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before();
beforeEach();
after();
afterEach();

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before(function(){
// ...
};
describe('with a subset of that thing', function() {
// Assertion tests
});
afterEach(function(){
// ...
};
});
});
setupTeardown

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asynchronousTests

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it('should not error', function(done) {
search.find("Apples", done);
});
asynchronousSyntax

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});
it('should return 2 items', function(done) {
search.find("Apples", function(err, res) {
if (err) return done(err);
res.should.have.length(2);
done();
});
});
asynchronousSyntax

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All Mocha functions accept this callback

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describe('When searching for Apples', function(done) {
before(function(done){
items.save(['fiji apples',
'empire apples'], done);
});
});
it('should return 2 items', function(done) {
search.find("Apples", function(err, res) {
if (err) return done(err);
res.should.have.length(2);
done();
});
});
});
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simplifyExecution

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$ mocha
should be simpliﬁed to
$ make test and $ npm test

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./makefile
# Makefile for sample module
test:
mocha --reporter spec --ui bdd
.PHONY: test
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./makefile
# Makefile for sample module
test:
mocha \
--reporter spec \
--ui bdd
.PHONY: test
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$ make test
Assertions

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./package.json
{
"name": "sample",
"version": "0.1.0",
"scripts": {
"test": "make test"
}
}
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$ npm test
Assertions

$ _

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eliminate global dependency
$ npm install mocha -‐-‐link

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test:
@./node_modules/.bin/mocha \
--reporter spec \
--ui bdd
.PHONY: test
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update dev dependencies
$ npm install mocha -‐-‐save-‐dev
$ npm install chai -‐-‐save-‐dev

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$ npm install mocha -‐-‐save-‐dev
$ npm install chai -‐-‐save-‐dev
$ git diff package.json
diff -‐-‐git a/package.json b/package.json
index 439cf44..3609bb9 100644
-‐-‐-‐ a/package.json
+++ b/package.json
@@ -‐1,5 +1,7 @@
{
"name": "sample",
-‐ "version": "0.1.0"
+ "version": "0.1.0",
+ "devDependencies": {
+ "mocha": "~1.9.0",
+ "chai": "~1.6.0"
+ }
}

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notiﬁcationSystems

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mocha --watch
continuousTesting
-w or --watch

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$ mocha -‐-‐watch
^ watching

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Growl

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mac:
win:
also:
apple app store
growlForWindows.com
growlNotify

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mocha --growl
growlNotiﬁcations
-G or --growl

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⌘S

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test:
--reporter spec \
--ui bdd
watch:
--reporter min \
--ui bdd \
--growl \
--watch
.PHONY: test watch
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mockingObjects

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JavaScript ships with a mocking framework
...it’s called JavaScript

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nock HTTP Mocking Library

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nock github:
install:
ﬂatiron/nock
npm install nock

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var http = require('http');
var reqOptions = {
host: 'api.twitter.com',
path: '/1/statuses/user_timeline.json?' +
'screen_name=jayharris'
};
// ...
http.request(reqOptions, resCallback).end();
// Returns live Twitter data
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var nock = require('nock');
var twitter = nock('http://api.twitter.com')
.get('/1/statuses/user_timeline.json?'+
'screen_name=jayharris')
.reply(200, "This worked");
// Returns "This worked"
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nock nock.recorder.rec( );
nock.recorder.play( );

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Spies, Stubs, & Mocks
Sinon.js

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github:
install:
cjohansen/Sinon.JS
npm install sinon
Sinon.js

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versionTesting

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nvm Node Version Manager

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nvm github:
github:
creationix/nvm
hakobera/nvmw

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$ nvm list
v0.4.0 v0.6.18 v0.8.21
v0.4.7 v0.8.1 v0.10.0
v0.6.0 v0.8.8
current:
v0.8.1
10 -‐> 0.10.0 (-‐> v0.10.0)
4 -‐> 0.4.7 (-‐> v0.4.7)
6 -‐> 0.6.18 (-‐> v0.6.18)
8 -‐> 0.8.21 (-‐> v0.8.21)
default -‐> 0.10.0 (-‐> v0.10.0)
newest -‐> 0.10.0 (-‐> v0.10.0)
$ _

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$ node -‐-‐version
v0.10.0
$ nvm install v0.10.6
Now using node v0.10.6
/Users/jayharris/.nvm/v0.10.6/bin/npm
$ node -‐-‐version
v0.10.6
$ _

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packageDistribution

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Package Manager

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./.npmignore
ﬁlePackaging

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npm adduser
userSetup

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$ npm adduser
Username: (jayharris) jayharris
Password:
Email: ([email protected]) _

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$ npm whoami
jayharris
$ _

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npm publish
packagePublish

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{ name: 'morale',
description: 'Async API wrapper for Morale',
'dist-‐tags': { latest: '0.2.0' },
versions:
[ '0.1.0',
'0.1.2',
'0.2.0' ],
maintainers: 'jayharris ',
time:
{ '0.1.0': '2012-‐01-‐23T03:24:59.824Z',
'0.1.2': '2012-‐01-‐25T23:20:52.927Z',
'0.2.0': '2012-‐08-‐13T16:23:28.488Z' },
author: 'Arana Software ',
repository:
{ type: 'git',
url: 'git://github.com/aranasoft/morale-‐node.git' },
users: { fgribreau: true },
version: '0.2.0',

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$ npm publish
npm http PUT https://registry.npmjs.org/morale
npm http 409 https://registry.npmjs.org/morale
npm http GET https://registry.npmjs.org/morale
npm http PUT https://registry.npmjs.org/morale/0.2.1/-‐tag/latest
npm http 201 https://registry.npmjs.org/morale/0.2.1/-‐tag/latest
npm http GET https://registry.npmjs.org/morale
npm http PUT https://registry.npmjs.org/morale/-‐/
morale-‐0.2.1.tgz/-‐rev/25-‐c9bbf49ea0bd2a750e257153fab5794b
npm http 201 https://registry.npmjs.org/morale/-‐/
morale-‐0.2.1.tgz/-‐rev/25-‐c9bbf49ea0bd2a750e257153fab5794b
+ [email protected]
$ _

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{ name: 'morale',
description: 'Async API wrapper for Morale',
'dist-‐tags': { latest: '0.2.1' },
versions:
[ '0.1.0',
'0.1.2',
'0.2.0',
'0.2.1' ],
maintainers: 'jayharris ',
time:
{ '0.1.0': '2012-‐01-‐23T03:24:59.824Z',
'0.1.2': '2012-‐01-‐25T23:20:52.927Z',
'0.2.0': '2012-‐08-‐13T16:23:28.488Z',
'0.2.1': '2012-‐08-‐30T19:10:20.133Z' },
author: 'Arana Software ',
repository:
{ type: 'git',
url: 'git://github.com/aranasoft/morale-‐node.git' },

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{ "private": "true" }
privatePackages

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./package.json
{
"name": "Sample",
"version": "0.1.0",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no tests avail.\" && exit 1"
},
"license": "BSD",
"private": "true"
}
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$ npm publish
npm ERR! Error: This package has been marked as private
npm ERR! Remove the 'private' field from the package.json to
publish it.
$ _

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npm shrinkwrap
versionLockdown

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$ npm shrinkwrap
wrote npm-‐shrinkwrap.json
$ _

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{
"name": "morale",
"version": "0.2.1",
"dependencies": {
"underscore": {
"version": "1.3.3"
},
"mocha": {
"version": "1.3.0",
"dependencies": {
"commander": {
"version": "0.6.1"
},
"growl": {
"version": "1.5.1"
},
"jade": {
"version": "0.26.3",
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$ rm npm-‐shrinkwrap.json
$ npm update
$ npm test
$ npm shrinkwrap

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tellEveryone

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Go make some Awesome

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jay harris
P R E S I D E N T
[email protected]
#nodemoduledev
@jayharris

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node.js Module Development

node.js Module Development

Jay Harris

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