require lookup behavior

require(X);

1. Is X a core module?
2. Is X a file path?
3. Is X a directory path?
4. Is X a module in node_modules?
5. Throw error

Core Module

var http = require('http');
var url = require('url');

File Path

var parser = require('./lib/parser.js');

var Assembler = require('../Assembler');

var users = require('../data/users.json');

Relative to thisFile.js

\-- project
    +-- Assembler.js
    +-- data
    |   \-- users.json
    |
    \-- src
        +-- thisFile.js
        \-- lib
            \-- parser.js

Directory Path

var cars = require('../../cars');

var util = require('./util');

+-- cars
|   +-- package.json
|   \-- ...
|
\-- project
    \-- src
        +-- thisFile.js
        \-- util
            \-- index.js

Module in node_modules

var _ = require('lodash');
var express = require('express');

\-- project
    +-- package.json
    +-- node_modules
    |   + -- lodash
    |   |    \-- ...
    |   | 
    |   \ -- express
    |        \-- ...
    |
    |-- thisFile.js
    \-- src
        \-- thisFile.js

require lookup behavior

1. Is X a core module?
2. Is X a file path?
3. Is X a directory path?
4. Is X a module in node_modules?
5. Throw error

Command Line

...Works the same way

.
+-- myDir
|   +-- package.json
|   +-- index.js
|   \...
|
+-- foo
|   +-- index.js
|   \...
|
+-- foo.js
\-- index.js

$ node ./foo.js
$ node .           
$ node myDir       
$ node foo

node-ecosystem/start/require-xyz/index.js

1. Add require statements to make your output:

   path/to/node-ecosystem/done/require-xyz/x.js
   path/to/node-ecosystem/done/require-xyz/y.js
   path/to/node-ecosystem/done/require-xyz/a/b/index.js
   Amici's
   Taco Gong
   Unfriendly's
   Shake Hovel
   Grey Castle
   

Hints:

1. Each .js file logs its path
2. Follow the comments
3. Paths are relative to the requiring file
4. json files can be loaded with require

Up Next: module.exports

var foo = require('./foo.js');

//basically means...

var foo = {{module.exports from the file 'foo.js'}}

module.exports = function add(x, y){ return y + x }

module.exports = "Hi there";

function Singleton(){
  //...
}

module.exports = new Singleton();

Consuming object literal API

// mathsConsumer.js

var maths = require('./myMaths.js');

console.log(maths.add(4, 6)); // 10
console.log(maths.div(9, 0)); // Infinity

// fsConsumer.js

var readFile = require('fs').readFile;

readFile('foo.txt', 'utf-8', function(err, contents){
  //...

node-ecosystem/start/multi-log.js

1. Use the logger.js module
2. Create a logger with prefix "DATABASE"
3. Create a logger with prefix "HTTP"
4. Log a message & and error from both

Hints:

1. See node-ecosystem/misc/logger-consumer.js for an example

Extra Credit:

1. Modify logger.js so loggers are enabled via environment variable

logfactory = require('./logger.js');

dblog  = logfactory('DATABASE');
applog = logfactory('MYAPP');

applog.l('boostraping...');
// MYAPP <Wed Jan 13 2016 16:54:55 GMT-0500 (EST)> bootstrapping...

dblog.l('SELECT * FROM users');
// DATABASE <Wed Jan 13 2016 16:54:55 GMT-0500 (EST)> SELECT * FROM users

Caching & Patching

// dog-stuff.js

module.exports = {
  name : 'Dog',
  noise : 'Bark!',
  bark : function(){
    console.log(this.noise);
  }
}

// perro.js
perro = require('./dogStuff');

perro.noise = '¡guau guau!'

// dogUser.js
dog = require('./dogStuff');
require('./perro');

dog.bark(); // ??