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<h1 style="text-align: center;">learn node.js in one hour</h1>
<h2>[WHAT]</h2>
<ol>
<li>] by Mosh H @ __ -&nbsp;</li>
</ol>
<h2>[WHY]</h2>
<ol>
<li>]&nbsp;</li>
</ol>
<h2>[WHERE]</h2>
<ol>
<li><strong>] WATCH THE FULL VIDEO<br /></strong></li>
<ol>
<li>]</li>
</ol></ol>
<h2>[WHEN]</h2>
<ol>
<li>] 2019-11-22</li>
</ol>
<h2>[EXAMPLE]</h2>
<ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=0s" target="_blank">[00:00</a>] What is Node</strong></li>
<ol>
<li>[] node is an open source, cross platform runtime environment for executing javascript code outside of the web browser</li>
<li>[] node is used for rapidly prototyping and agile development</li>
<li>[] node is used for building backend services like apis that power client applications, like web and mobile clients</li>
<li>[] <strong>fast</strong> -</li>
<ol>
<li>[] <span style="background-color: #c0c0c0;">[] node uses a non blocking <br /></span></li>
<li><span style="background-color: #c0c0c0;">[] asynchronous architecture by default</span></li>
</ol>
<li>[] <strong>scaleable</strong> -</li>
<ol>
<li><span style="background-color: #c0c0c0;">[] node is&nbsp; built using an event driven architecture, </span></li>
</ol>
<li><strong>[x] adoption</strong> - used by large companies like Paypal, walmart</li>
<li>[] <strong>study</strong> by paypal found that company developers were able to build app twice as fast with fewer people, <strong>33% less lines</strong> of code, <strong>40% fewer files</strong>, <strong>2x requests per sec</strong> and&nbsp; <strong>35% faster response times</strong></li>
<li>[] use <strong>javascript everywhere</strong> - developers can use 1 programming language on both the front end and the back end of the application, using the same naming conventions, the same tools, the same best practices results in cleaner code</li>
<li>[] <strong>the largest ecosystem</strong> of pre built components -</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=181s" target="_blank">[03:01</a>] Node Architecture</strong></li>
<ol>
<li>[] earlier, we learned that node is a javascript runtime environment</li>
<li>[] there are a variety of js engines that exist, chakra in IE, spidermonkey in firefox, v8 in chrome,</li>
<li>[] the different engines in each of the different browser sometimes results in javascript behaving differently in&nbsp;</li>
<li>[] while the browser has window or document object to interact with, node does not</li>
<li>[] before 2009, the only way to execute javascript code was in a web browser</li>
<li>[+*] windows had/has a 'windows scripting host' which enabled the execution of js on the windows OS platform</li>
<li>[+*] window 8 app development platform was based on winjs, using js + html + css to build native windows 8 apps with web technologies&nbsp;</li>
<li>[] in 2009, ryan dahl embedded the chrome browsers js engine(v8), inside a c++ program and called it node</li>
<li>[] node has no window or document object like the browser has,</li>
<li>[] but node has its own set of objects that you can use to work with different things</li>
<li>[] examples of node objects include things like = ] fs, ] http, ] os, ] global ] console</li>
<li>[] node = v8 javascript engine + additional objects</li>
<li>[]</li>
<li><strong>[] node is NOT a programming language, it is NOT a framework</strong></li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=364s" target="_blank">[06:04]</a> How Node Works</strong></li>
<ol>
<li>[] node has a non blocking or asynchronous architecture by default</li>
<li>[*] ASYNCH waiter example - ] waiter takes your order, ] goes to kitchen, ] takes next customers order, ] goes to kitchen, ] when your order is ready&nbsp;</li>
<li>[*] SYNCH - - ] waiter takes your order, ] goes to kitchen, ] waits at kitchen until your order is ready ] returns with your order ] takes next customers order, ] ...</li>
<li>[] thread allocated from server, often getting data from db takes time,</li>
<li>[] if a bunch of threads are</li>
<li>[] at some point, you will run out of threads and ...</li>
<li>[] <strong>USE NODE for</strong> data intensive apps and realtime apps, apps with a lot of i/o,</li>
<li>[] <strong>DONT USE NODE for</strong> cpu intensive apps like ] video encoding, ]</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=629s" target="_blank">[10:29</a>] Installing Node</strong></li>
<ol>
<li>[] use &gt;node --version // from a command prompt, to test if you have node installed</li>
<li>[] <a href="https://nodejs.org" target="_blank">nodejs.org</a> - has the latest stable version and the latest version(experimental, maybe not stable)</li>
<li>[] download and install your preferred version, installer is simple and straightforward</li>
</ol>
<li><strong><a class="yt-simple-endpoint style-scope yt-formatted-string" href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=781s">[13:01]</a> Your First Node Program</strong></li>
<ol>
<li>[] create first app by defining a javascript function in a file named app.js</li>
<li>[] execute the program by launching node with the application file name as an arguement</li>
<li>[] &gt;node app.js</li>
<li>[]&nbsp; demonstrates that there really is no window or document object in node</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=922s" target="_blank">[15:22]</a> Node Module System</strong></li>
<ol>
<li>[] what the module system is</li>
<li>[] why we need them</li>
<li>[] built in modules ] filesytem ] http,] events, ] os , ] global, ] ...</li>
<li>[] how to create your own modules - ] myModule</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=952s" target="_blank">[15:52]</a> Global Object</strong></li>
<ol>
<li>[] console object is a global object, part of the global scope, it is available anywhere</li>
<li>[] other global objects include methods like, ] setTimeout, ] clearTimeout ] setInterval, ] clearInterval</li>
<li>[] just like the standard global js objects</li>
<li>[] other node global objects</li>
<li>[] remember there is no global window aka document object</li>
<li>[] object called 'global' contains it global methods</li>
<li>[] global.console.log -</li>
<li>[] shorthand console.log -</li>
<li>[] var and functions declared/defined in a module (file) are only scoped to that file,&nbsp;</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=1154s" target="_blank">[19:14</a>] Modules</strong></li>
<ol>
<li>[] A problem with having a global scope like in browser js, is that often applications have multiple js files, any file that declares a var with the same name as declared in another file will cause problems with the application js execution</li>
<li>[] create modules or functions that encapsulate specific functionality</li>
<li><strong>&gt; [] every file in a node application is considered a module</strong></li>
<li>[] vars and functions defined in the file are scoped to just that file, in OOP terms they are 'private'</li>
<li><strong>[] if you want to use a var or function defined in a module, outside of the file it is defined in, you need to explicitly EXPORT that var or function</strong></li>
<li>[] every node application has at least 1 file, which is considered to be its 'main module'</li>
<li>[]&nbsp;</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=1371s" target="_blank">[22:51]</a> Creating a Module</strong></li>
<ol>
<li>[] using module.exports.log = log to export a function that you want to make available</li>
<li>[] using module.exports.url = url to export a variable or property that you</li>
<li>[] only export the required functionality, not the implementation details</li>
<li>[] metaphor - dvd player - only has a few buttons on the outside to operate it, however there is lots of complexity inside the unit, what are your modules buttons</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=1655s" target="_blank">[27:35]</a> Loading a Module</strong></li>
<ol>
<li>[x] use require statement to load the desired module in the file that will consume it</li>
<li>[x] require takes one arg, the name or path to the module file</li>
<li>[*] .js extension on files is assumed by node, so it is not necessary</li>
<li>[x] use ./ prefix for module files that are located in the same directory as the file that will be using the file</li>
<li>[x] best practice to now use const logger = require(logger) VS using var logger = ... // prevents use from accidentally re-assiging the logger functionality</li>
<li>[] using jshint -</li>
<li>[x] ALSO OPTION - dont have to export as object, can export as function,</li>
<li>[x] in module - module.exports = log</li>
<li>[x] in consuming module -&nbsp; const logger = require('..'), NO need for logger.log('message'), can use by calling logger('message' )</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=1979s" target="_blank">[32:59</a>] Module Wrapper Function</strong></li>
<ol>
<li>[] node does not execute the code in your modules directly, it wraps your code inside of its own function wrapper</li>
<li>[] wrapped inside an iife function, has args like ( exports, require, module, __filename, __dirname )</li>
<li>[] console.log(__filename);</li>
<li>[] node comes with a bunch of useful modules we can use</li>
</ol>
<li><strong>[] AD - inline</strong></li>
<ol>
<li>[*] inline AD for moshes <a href="https://codewithmosh.com/p/the-complete-node-js-course" target="_blank">complete course</a> , currently $29 for lifetime access , 15 hours material, restful api with node, express, mongodb, this videos content is the first segment(module) of # segments total, additional segments cover</li>
<li>[] using npm,</li>
<li>[] building restful apis using expressjs</li>
<li>[] express advanced topics,</li>
<li>[] asynch javascript,</li>
<li>[] crud operations using mongoose</li>
<li>[] mongo data validation</li>
<li>[] mongoose modelling relationships between connected data[]</li>
<li>[] authentication and authorization[73:00]</li>
<li>[] handling and logging errors[63:00]</li>
<li>[] unit testing [61:15]</li>
<li>[] integration testing [69:00]</li>
<li>[] test driven development[57:00]</li>
<li>[] deployment[28:00] &nbsp;</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=2393s" target="_blank">[39:53</a>] Path Module</strong></li>
<ol>
<li>[] a quick look at some of the common native/built in modules that come with nodejs</li>
<li>[] documentation at nodejs.org -&gt; docs -&gt; select your version -&gt; table of contents</li>
<li>[] not everything listed here is a module,</li>
<li>[] some are global objects, like the console object,</li>
<li>[] common modules include [] filesystem, [] http, [] os [] path, [] process, [] querystrings, [] stream</li>
<li>[] example - using the path module</li>
<li>[] easier to use the path module methods then working with strings</li>
<li>[1] const path = require('path');</li>
<li>[*] if no path to the modulename is provided in the arg to the require methdo, node assumes that it is a built in module, if no built in module exists, node ...</li>
<li>[2] let pathObject = path.parse(__filename); // filename here is the __filename of the current module</li>
<li>[3] console.log(pathObject.name) // returns 'app' which is the filename without the file extension,</li>
<li>[*] other 'path object' properties include root, dir, ext and base</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=2643s" target="_blank">[44:03]</a> OS Module</strong></li>
<ol>
<li>[x] reviewing official docs for methods available in the os module</li>
<li>[x] demonstrates using os module methods to get total memory and free memory on the current system</li>
<li>[x] demonstrates using template strings (vs concatenations), remember backticks and ${var}, see example below</li>
<li>[<strong>x] var displayString = `the total value of the property is: {$totalValue}`</strong></li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=2902s" target="_blank">[48:22]</a> File System Module</strong></li>
<ol>
<li>[x] reviewing official docs for methods available in the filesystem module</li>
<li>[x] almost every fs method comes in 2 forms, synch or asynch</li>
<li>[*] remember the node process is a single thread, if the process is blocked waiting for something, it cant continue to serve additional requests</li>
<li>[x] example - read the current directory and output a list of the files it contains</li>
<li>[x] example - read the current directory and pass callback to execute, if error exists with fs call, it gets passed, can then handle error aka, else list files</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=3194s" target="_blank">[53:14</a>] Events Module</strong></li>
<ol>
<li>[] core concept of node, event is a signal that something has happened</li>
<li>[] req</li>
<li>[] docs - events module</li>
<li>[] example events emitter (ee),</li>
<li>[] ee is a class, note the difference in instatntiating an instance of, have to use the new operator&nbsp;</li>
<li>[] describes object, class human, object john</li>
<li><strong>[] // raise an event</strong></li>
<li>[x] &gt;emitter.emit() // making a noise, a signal, that something has happened</li>
<li>[x] pass it the arguement of the name of the event,</li>
<li>[x] &gt;emitter.emit('messageLogged')</li>
<li><strong>[] // NOW we need to listen for the event</strong></li>
<li>[] emitter.on() || emitter.addListener()</li>
<li>[] arguements for the listener include the name of the event to listen for and a callback function</li>
<li><strong>[] // register a listener</strong></li>
<li>[x] &gt; emitter.on('messageLogged', function(){ console.log('message log event handler firing')})</li>
<li>[!*] the order of the declaration is important</li>
<li>[x] the event listener/handler must be declared before the event emitter</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=3573s" target="_blank">[59:33</a>] Event Arguments</strong></li>
<ol>
<li>[] you can also pass data about the event that just happenend to the event handler by using additional arguements</li>
<li>[] in the event emit function, include the data about the event that you want to pass into the event handler</li>
<li>[] emitter.emit('messageLogged', {id:3, name:"elm Name"});</li>
<li>[] in the event handler function, accept the passed args and process them</li>
<li>[] emitter.on('messageLogged', function(args){ console.log(args) }</li>
<li>[] mentions using es6 arrow functions vs function keyword</li>
<li>[] emitter.on('messageLogged', (args)=&gt;{ console.log(args); }</li>
<li>[] exersize = create an event for your logger</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=3763s" target="_blank">[01:02:43]</a> Extending EventEmitter</strong></li>
<ol>
<li>[] i put the event emitter constructs in the logging module</li>
<li>[] then I raised the logging event in the logging module but the event handler was not getting called</li>
<li>[] he does the same with the same result and then explains how we are working with 2 different event emitter objects, 1 in app, 1 in logging</li>
<li>[] so we need to make the logger into a class</li>
<li>[] make the current logger function as a method in the class</li>
<li>[] and export the class (versus the function) in the module exports</li>
<li>[] we then instantiate an instance of the Logger class, in the app module</li>
</ol>
<li><strong><a href="https://www.youtube.com/watch?v=TlB_eWDSMt4&amp;t=4246s" target="_blank">[01:10:46]</a> HTTP Module</strong></li>
<ol>
<li>[x] one of the powerful building blocks of node,</li>
<li>[x] can create a web server, that listens for http requests,</li>
<li>[x] node docs</li>
<li>[x] server is an eventEmitter, - has on method, close method and more,</li>
<li>[x] inherits from .net server,</li>
<li>[x] common usage, pass a callback function into create server, with request and response args,</li>
<li>[x] example handling http requests in</li>
<li>[x] CC my project nodeOne - app.js</li>
<li>[x] wont be using this to build a server, will be using framework(expressjs) to keep things clean/modular</li>
</ol></ol>
<h2>[HOW-TO]</h2>
<ol>
<li>]</li>
</ol>
<h2>[REFERENCE]</h2>
<ol>
<li>] SRC = HN, comments</li>
<li>[] book - nodejs - table of contents</li>
<li>[] article - node.js - <a href="/view/article?id=4500" target="_blank">overview</a></li>
</ol>
<h1 style="text-align: center;">&nbsp;</h1>

~ view article ~ Chapter] ch-009-how-to FROM [ Book] nodejs IN [ libraries] technology-developer-www