#most common NODE JS interview questions | Explore Tumblr posts and blogs

udemytutorialfreedownload · 5 years ago

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Node JS: Advanced Concepts

Get advanced with Node.Js! Learn caching with Redis, speed up through clustering, and add image upload with S3 and Node!

What Will I Learn?

Absolutely master the Event Loop and understand each of its stages

Utilize Worker Threads and Clustering to dramatically improve the performance of Node servers

Speed up database queries with caching for MongoDB backed by Redis

Add automated browser testing to your Node server, complete with continuous integration pipeline setup

Apply scalable image and file upload to your app, utilizing AWS S3

READ ALSO :

Learn Flutter & Dart to Build iOS & Android Apps [2020]

Blockchain and Bitcoin Fundamentals

Requirements

Basic knowledge of Node, Express, and MongoDB

Strong knowledge of Javascript

Description

Go beyond the basics of Node! This course will give you the skills needed to become a top Node engineer. Query Caching with Redis? You will learn it. The Node Event Loop? Included. Scalable File Upload? Of course! This is a must-take course if you work with Node. Node Internals: Here’s one of the most common interview questions you’ll face when looking for a Node job: “Can you explain the Node’s Event Loop?” There are two types of engineers: those who can describe the Event Loop and those who cannot! This course will ensure that you are incredibly well prepared to answer that most important question. Besides being critical for interviews, knowledge of the Event Loop will give you a better understanding of how Node works internally. Many engineers know not to ‘block’ the Event Loop, but they don’t necessarily understand why. You will be one of the engineers who can clearly articulate the performance profile of the Node and its Event Loop.

Caching with Redis:

We’ll also supercharge the performance of database queries by implementing caching backed by Redis. No previous experience with Redis is required! Redis is an in-memory data store purpose-built for solving caching needs. By adding caching to your application, you can decrease the amount of time that any given request takes, improving the overall response time of your app.

File Upload:

There are many resources online that offer suggestions on how to handle file upload, but few show a solution that can truly scale. Hint: saving files directly on your server isn’t a scalable solution! Learn how to leverage AWS S3 to implement file upload that can scale to millions of users with a few dozen lines of simple code. Plentiful discussions are included on security concerns with handling uploads, as well.

Continuous Integration Testing:

This is a must-have feature for any serious production app. We’ll first learn how to test huge swaths of our codebase with just a few lines of code by using Puppeteer and Jest. After writing many effective tests, we��ll enable continuous integration on Travis CI, a popular – and free – CI platform. Testing can sometimes be boring, so we’ll use this section to brush up on some advanced Javascript techniques, including one of the only legitimate uses of ES2015 Proxies that you’ll ever see!

Here’s what we’ll learn:

Master the Node Event Loop – understand how Node executes your source code.

Understand the purpose of Node, and how the code you write is eventually executed by C++ code in the V8 engine

Add a huge boost to performance in your Node app through clustering and worker threads

Turbocharge MongoDB queries by adding query caching backed by a lightning-fast Redis instance

Scale your app to infinity with image and file upload backed by Amazon’s S3 file service

Implement a continuous integration testing pipeline so you always know your project functions properly

Think you know everything there is about managing cookies and session? Well, you might, but learn even more!

Ensure your app works the way you expect with automated browser testing using Jest and Puppeteer

Bonus – learn advanced JS techniques along the way, including where to use ES2015 proxies!

I’ve built the course that I would have wanted to take when I was learning to Node. A course that explains the concepts and how they’re implemented in the best order for you to learn and deeply understand them.

Who is the target audience?

Anyone who wants a deep mastery of Node

Engineers looking to understand the internals of Node

Programmers looking to improve Node’s performance

Created by Stephen Grider Last updated 3/2020 English English [Auto-generated] Size: 1.76 GB

DOWNLOAD COURSE

#News Updates #Node JS: Advanced Concepts

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t-baba · 5 years ago

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The most popular JavaScript links of 2019

#469 — January 3, 2020

Read on the Web

JavaScript Weekly

The holiday season is rapidly coming to a close and we're looking forward to not only a new year but the entirety of the Roaring Twenties. Rest assured, the JavaScript world is not going to look the same when 2030 turns up so watch this space! 😄

We'll be back as usual next week, but this week we're taking a look back at 2019 and the most popular things you clicked on. If you didn't read every issue in 2019 (we wouldn't expect you to!) you'll hopefully find a few things worth revisiting here.

Thanks for supporting us — we look forward to keeping you up-to-date in the years to come.

— Peter Cooper and the Cooperpress team

📈 Our most popular links of 2019:

1. The TypeScript Tax: A Cost vs Benefit Analysis — As much as we love JavaScript, this was really a strong year for TypeScript, with it seeming to become the de facto way to bring strong typing to JavaScript. Back in January, Eric Elliott asked "is it worth it?" and presented some critical, data-driven analysis to establish its viability. It was your most clicked link of 2019.

Eric Elliott

2. New ES2018 Features Every JavaScript Developer Should Know — We're now looking forward to ES2020 and we've had ES2019 in 2019 too, but this post remains packed with interesting examples of spread properties within object literals, asynchronous iterators and asynchronous iterables, Promise.prototype.finally, and other features that are still not exactly common to see in the wild.

Faraz Kelhini

The Complete ⚛️ React Learning Path — Take your React to the next level to find out what it is fully capable of with this comprehensive learning path.

Frontend Masters sponsor

3. 43 JavaScript Questions, With Their Answers Explained — Whether for fun or a job interview, this remains an interesting set of JavaScript-related questions, complete with explanations of the answers.

Lydia Hallie

4. I Don't Hate Arrow Functions (But..) — Arrow functions (=>), as introduced in ES6, have generally been a much welcomed addition to JavaScript but Kyle Simpson reminded us they’re not suitable in every scenario and created an ESLint plugin to help you keep a handle on their use.

Kyle Simpson

5. Responsible JavaScript: A Three Part Series — We originally only linked to part one of this great series where Jeremy Wagner plotted a course to avoid the unnecessary bloat and inaccessible patterns of modern JavaScript trends.. but now you can enjoy part 2 and part 3 too, where he went into more technical depth on bundling and handling third-party scripts.

Jeremy Wagner

6. What’s New in JavaScript — At this year’s Google I/O ’19, Mathias Bynens and Sathya Gunasekaran of the V8 team gave a fantastic 30 minute ‘state of the union’ talk on the state of JavaScript as a language and what new features are being baked in.

Google I/O video

💻 Jobs

JavaScript Developer at X-Team (Remote) — Work with the world's leading brands, from anywhere. Travel the world while being part of the most energizing community of developers.

X-Team

Senior Software Engineer, Frontend — Use the latest tech to mold an innovative, empathy-centric experience for creators to order fast, high-quality parts (forging space robots to animatronics).

Fictiv

Find a Job Through Vettery — Vettery is completely free for job seekers. Make a profile, name your salary, and connect with hiring managers from top employers.

Vettery

📘 The most popular articles & tutorials of 2019

The Cost of JavaScript in 2019 — Addy Osmani presented a 2019 update to his Cost of JavaScript in 2018 article in both video and article forms. If you still want to get a feel for where the true bottlenecks are with JavaScript, this is a must read.

Addy Osmani

Should We Rebrand 'JavaScript'? — This thoughpiece provoked quite a bit of discussion in the community over the problems (or not) with ‘JavaScript’ as a name. I think we'll see more on this front in 2020.

Kieran Potts

First Online Mentored Software Bootcamp w/ Job Guarantee — Get a job or your money back with Springboard’s online bootcamp. Benefit from 1:1 mentorship, our exclusive curriculum, and top career coaching.

Springboard (Software Engineering Career Track) sponsor

When Should You Be Using Web Workers? — Web Workers provide a way to run JavaScript in background threads in the browser and you’d think using them as much as possible would be a good thing.. right? Current frameworks make this tough, says Surma, who shows us why we should be working to change this ASAP.

Surma

Practical Ways to Write Better JavaScript — You’re not necessarily going to agree with all of them (e.g. “Use TypeScript”!) but this is a reasonably solid batch of points to think about overall.

Ryland Goldstein

JavaScript Symbols: But Why? — Not played with symbols (a new data type introduced with ES6) yet? This is a gentle way to get up to speed with not only what they are but why you might use them.

Thomas Hunter II

Make 2020 the Year to Master MongoDB. Try Studio 3T Today — Generate driver code for JavaScript, Python, Ruby and more? Build queries fast with our drag & drop editor? Of course.

Studio 3T sponsor

Using Native JavaScript Modules in Production Today — “now, thanks to some recent advances in bundler technology, it’s possible to deploy your production code as ES2015 modules—with both static and dynamic imports—and get better performance than all non-module options currently available.”

Philip Walton

7 Tricks with Resting and Spreading JavaScript Objects — Using modern JS features to merge objects, organize properties, and more.

Joel Thoms

📺 The most popular videos of 2019

▶ Why I Was Wrong About TypeScript — Smells like an opinion-driven talk, but actually covers the history behind compile-to-JS languages, how we got to a point where interest in TypeScript is growing strongly, and why it’s worth taking seriously.

TJ VanToll

▶ Why 0.1 + 0.2 === 0.30000000000000004: Implementing IEEE 754 in JS — Head to your node CLI right now and type in 0.1 + 0.2. If the answer confuses you, this is the video for you. And even if you know why, working with the building blocks behind floating point representations is just cool anyway.

Low Level JavaScript

Video Developer Report - Top Trends in Video Technology 2019

Bitmovin sponsor

▶ Keep Betting on JavaScript — Kyle Simpson presents a history lesson of JavaScript, looks at how a variety of features were (or weren’t) introduced, and compels us to think about the future of the Web and JavaScript as we contribute and ‘place bets’ on technologies.

Kyle Simpson

▶ A Look at Deno: A New(ish!) JavaScript Runtime — Ryan originally created Node about ten years ago but over the past couple of years he’s been working on Deno, a non-Node compatible, TypeScript-focused runtime with some interesting features. (Note: Poor audio until a few minutes in.) I suspect we'll hear a lot more about this in 2020.

Ryan Dahl

🔧 The most popular code & tool releases of 2019

Svelte 3 Released: Rethinking Reactivity — Svelte is one of the most interesting UI frameworks out there as it’s not scared of taking a unique approach. Rather than running in the browser, Svelte runs at build time, compiling your app into more efficient runtime JavaScript. Svelte 3 took some major steps forward, particularly in helping you write less code.

Rich Harris

Mithril.js 2: A JavaScript Framework for Building Brilliant Applications — Mithril is a really neat alternative to things like Vue, React or Angular. It’s very compact and fast (so ideal for mobile), runs a bit closer to vanilla JS than the alternatives, and is great for tying together vanilla JS libraries rather than needing its own alternatives.

Mithril

RunJS: A JavaScript 'Scratchpad' Tool for the Desktop — Write and run JavaScript instantly. Useful for learning, experimenting, or perhaps even creating screencasts, tweets, or similar educational content. Originally macOS only but now supports Windows and Linux too.

Luke Haas

Pixi.js 5: Create Beautiful 2D Web Experiences — Boasts the ‘fastest, most flexible 2D WebGL renderer’ to let you take advantage of hardware acceleration without getting involved in WebGL or 3D concerns. Check out demos for what the code looks like and what you’d use it for. There’s also a Pixi Playground for quickly crafting your own experiments.

PixiJS

Babylon.js 4.0: The (Very) Powerful WebGL Graphics Engine — Such a significant release that they released a 2 minute video trailer for it! Want to play? Enjoy this editable live demo.

Microsoft

Postwoman: An API Request Builder and Tester — A free alternative to Postman, a popular app for debugging and testing HTTP APIs. Postwoman works in the browser and supports HTTP and WebSocket requests as well as GraphQL. Insomnia is a similar tool if you want to run something as a desktop app.

Liyas Thomas

FlexSearch.js: A Full Text Search Library — Claims to outperform all of the alternatives while supporting features like multi-word matching and phonetic transformations. Happy in both the browser and Node.js.

Nextapps GmbH

Just: A JavaScript Task Library from Microsoft — If you’re familiar with Ruby’s rake, it’s a bit like that. Define tasks in JavaScript, run them with just (which works fine without installation using npx) and you get a bunch of nice features like logging and task composition.

Microsoft

Node-RED 1.0 Released — Node RED is a flow-based, visual programming tool (aimed primarily at hardware automation) that’s built on top of Node.js. Despite only reaching 1.0 in 2019, it’s a mature project used in numerous real world IoT projects.

Nick O'Leary

by via JavaScript Weekly https://ift.tt/2QHifL3

#Javascript Branding #Javascript Weekly

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siva3155 · 6 years ago

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300+ TOP Ext JS Interview Questions and Answers

Ext JS Interview Questions for freshers experienced :-

1. What is Ext Js? Ext JS stands for extended JavaScript. It is a JavaScript framework to develop rich UI web based desktop applications. 2. Why did you choose Ext JS? The overall design of extjs is exemplary.One can learn a lot from it’s unified architecture – no matter which language one is programming in. Extjs requires you to start with one of their base classes – ensuring a consitent model. Consistency is extremely important for the library to be reusable. Extjs documentation seems to be very comprehensive and well maintained. key aspect of the EXTJS Library is the cross-browser support. Build rich Internet applications with Ext JS Ext JS framework is the multitude of rich UI elements provided. These elements include forms, dialog boxes, tabs, trees, and grids. The Ext JS framework includes support for Ajax implementations. Ext JS integration with other Web server frameworks. Ext JS framework development into several popular integrated development environments (IDEs), including Eclipse, Aptana, and Komodo. Ext JS provides excellent performance.The framework is fully object oriented and extensible. Because it’s written in the JavaScript language 3. What are major Web browsers supported by Ext JS framework? Windows® Internet Explorer® version 6 and later. Mozilla Firefox version 1.5 and later (PC and Macintosh). Apple Safari version 2 and later. Opera version 9 and later (PC and Mac). 4. Integration of Web development server-side frameworks with Ext JS? You can use Ext JS with other common Web development server-side frameworks, including PHP, the Java™ language, Microsoft® .NET, Ruby on Rails, and ColdFusion. 5. Where Extjs extended from ? Ext JS as a project to extend the functionality that the YUI Library.A key aspect of the YUI Library is the cross-browser support.The Extjs framework is fully object oriented and extensible. Because it’s written in the JavaScript language. 6. Extjs Ajax implementation? A typical Ext JS Ajax implementation: an HTML text field and button element that posts data in the text field to a Web server when the button is clicked. 7.Do you have any advice for developers using Ext for the first time? Ext can be used by Web Application developers who are familiar with HTML but may have little or no experience with JavaScript application development. If you are starting to build a new web application, or you are revamping an existing application, then take your time to understand the basics of the library including. 8. How to access Dom element using EXTJS? The Element API is fundamental to the entire Ext library. Using traditional Javascript, selecting a DOM node by ID is done like this: var myDiv = document.getElementById(‘myDiv’); Using Extjs: Ext.onReady(function() { var myDiv = Ext.get(‘myDiv’); }); 9. what is the purpose of Element Object in Extjs? Element wraps most of the DOM methods and properties that you’ll need, providing a convenient, unified, cross-browser DOM interface (and you can still get direct access to the underlying DOM node when you need it via Element.dom) The Element.get() method provides internal caching, so multiple calls to retrieve the same object are incredibly fast The most common actions performed on DOM nodes are built into direct, cross-browser Element methods (add/remove CSS classes, add/remove event handlers, positioning, sizing, animation, drag/drop, etc.) 10. what is syntax for Ext js Button click event? Ext.onReady(function() { Ext.get(‘myButton’).on(‘click’, function(){ alert(“You clicked the button”); }); }); ulating it. 11. what is use of Ext.onReady() function ? Ext.onReady is probably the first method that you’ll use on every page. This method is automatically called once the DOM is fully loaded, guaranteeing that any page elements that you may want to reference will be available when the script runs syntax: Ext.onReady(function() { alert(“Congratulations! You have Ext configured correctly!”); }); 12. For example, to show our message when any paragraph in our test page is clicked, what is the extjs code on paragraph click? Ext.onReady(function() { Ext.select(‘p’).on(‘click’, function() { alert(“You clicked a paragraph”); }); }); or Ext.onReady(function() { var paragraphClicked = function() { alert(“You clicked a paragraph”); } Ext.select(‘p’).on(‘click’, paragraphClicked); }); 13. List out the extjs library files to include in JSP page? ext-base.js ext-all-debug.js or ext-all.js ext-all.css base.css or examples.css 14. List out the css file required to apply Extjs Theme property? xtheme-gray.css ext-all.css 15. what is purpose of MessageBox? MessageBox is asynchronous. MessageBox call, which demonstrates the readable message to user. MessageBox used for multiple purpose like Ext.Msg.alert() Ext.Msg.prompt() Ext.Msg.show({}); Ext.Msg.wait(); 16. write syntax for MessageBox show() method? Ext.MessageBox.show({ title: ‘Paragraph Clicked’, msg: ‘User clicked on Paragraph’, width:400, buttons: Ext.MessageBox.OK, animEl: paragraph }); 17. what is method to Update the message box body text for MessageBox? updateText( ) : Ext.MessageBox 18. what is a widget? A widget is a tiny piece or component of functionality. 19.what is parent class for all stores in extjs? how many stores exists? Ext.data.Store is parent class for all stores. A Store object uses its configured implementation of DataProxy to access a data object unless you call loadData directly and pass in your data. subclasses for Store: GroupingStore, JsonStore, SimpleStore 20. How to handle event for a extjs component? using listeners config object. For ex for grid events : listeners: {rowclick: gridRowClickHandler,rowdblclick: gridRowDoubleClickHandler} using addListener( String eventName, Function handler, , ) : void Appends an event handler to this component using on( String eventName, Function handler, , ) : void Appends an event handler to this element (shorthand for addListener) For ex: store.on( “datachanged”, function( store ){ ….. }); 21. How to find no of records in a store? using store.getCount() : Gets the number of cached records. store.getTotalCount() : Gets the total number of records in the dataset as returned by the server. 22. How to handle exception while loading datastore? using loadexception event. syntax: store.loadexception() : Fires if an exception occurs in the Proxy during loading. use beforeload : ( Store this, Object options ) : Fires before a request is made for a new data object. If the beforeload handler returns false the load action will be canceled. syntax: store.on(‘loadexception’, function(event, options, response, error) { alert(“Handling the error”); event.stopEvent(); }); 23. how to handle updates for store changes? use store.commitChanges() 24. what is the purpose of each() in store? Calls the specified function for each of the Records in the cache each( Function fn, ) 25. how to get modified records using store object? store.getModifiedRecords() : Gets all records modified since the last commit. 26. how to get record using index? store.getAt( Number index ) : Get the Record at the specified index. 27. how to get record using id? store.getById( String id ) : Get the Record with the specified id. 28. what is the purpose of load() in store? store.load() : returns boolean Loads the Record cache from the configured Proxy using the configured Reader. For remote data sources, loading is asynchronous, and this call will return before the new data has been loaded. store.load({callback: fnCheckData, scope: this}); 29. what is purpose of loadData() in store? store.loadData( Object data, ) : void Loads data from a passed data block and fires the load event. loadData(storeData,false); False to replace the existing records cache. loadData(storeData,true) : True to append the new Records rather than replace the existing cache. 30. How many types of layout managers exist in extjs?what are they? Layouts fall under this package Ext.layout.* Types of layouts: Absolute Layout: This is a simple layout style that allows you to position items within a container using CSS-style absolute positioning via XY coordinates. Accordion Layout: Displays one panel at a time in a stacked layout. No special config properties are required other than the layout. All panels added to the container will be converted to accordion panels. AnchorLayout: This type of layout is most commonly seen within FormPanels (or any container with a FormLayout) where fields are sized relative to the container without hard-coding their dimensions. BorderLayout: Border layouts can be nested with just about any level of complexity that you might need. Every border layout must at least have a center region. All other regions are optional. CardLayout (TabPanel): The TabPanel component is an excellent example of a sophisticated card layout. Each tab is just a panel managed by the card layout such that only one is visible at a time CardLayout (Wizard): You can use a CardLayout to create your own custom wizard-style screen. FitLayout: A very simple layout that simply fills the container with a single panel. FormLayout: FormLayout has specific logic to deal with form fields, labels, etc.FormLayout in a standard panel, ColumnLayout: This is a useful layout style when you need multiple columns that can have varying content height.Any fixed-width column widths are calculated first, then any percentage-width columns specified using the columnWidth config TableLayout: Outputs a standard HTML table as the layout container.you want to allow the contents to flow naturally based on standard browser table layout rules. data, plus manip 31. How we can apply pagination in grid panel ? using Ext.PagingToolbar plugin, we can implement pagination to a grid panel syntax: new Ext.PagingToolbar({ pageSize: 25, store: store, displayInfo: true, displayMsg: ‘Displaying topics {0} – {1} of {2}’, emptyMsg: “No topics to display”, }) // trigger the data store load store.load({params:{start:0, limit:25}}); 32. what is xtype? The xtype will be looked up at render time up to determine what type of child Component like TextField, NumberField etc to create. i,e xtype = Class ———————- button = Ext.Button textfield = Ext.form.TextField radio – Ext.form.Radio grid = Ext.grid.GridPanel combo = Ext.form.Combobox toolbar = Ext.Toolbar 33. what is vtype? The validations provided are basic and intended to be easily customizable and extended. Few vtypes provided by extjs are as below: emailText : String, The error text to display when the email validation function returns false alphanumText : String, The error text to display when the alphanumeric validation function returns false urlText : String, The error text to display when the url validation function returns false 34.Why we need javascript Library? Javascript is an awesome language. It’s super flexible.Browsers are the modern UI paradigm. The javascript Libraries now must provide a rich set of UI Widgets. javascript libraries: JQuery Qooxdoo Dojo Prototype.js mootools extjs 35.how to get record object from store: var record = grid.getStore().getAt(rowIndex); 36. purpose of Load mask? To apply mask to page level / component level. restrict user not to access any components in page var pageProcessBox = new Ext.LoadMask( Ext.getBody(), { msg: ‘Loading Employee details.’ } ); pageProcessBox.show(); 37. purpose of renderer in grid panel? using config option, renderer: fnCellColor where fnCellColor is method to apply color to a cell. 38. how to get selection model used in a grid panel? using grid.getSelectionModel(); method 39. how to stop editing a record? newRecord.endEdit(); 40. how to start editing a record? newRecord.beginEdit(); 41. how to commit a record modification? newRecord.commit(); 42. what is use of combo select event function? To get the selected value from a combo.using getvalue(); var selectedComboValue = mycombo1.getValue(); 43. how to get a value of textfield or combo box? using getvalue(); var selectedValue = mytextfield.getValue(); 44. how to apply css on select of combo box? using config option as emptyClass : ’emptycss’, where emptycss is a css classname 45. what are components required for grid panel? store, columnmodel, id, width,height 46. how to disable menu option for header in columnModel? using menuDisabled: true 47. how to hide the column in grid panel? using hidden : true 48. How to register callbacks to the load and exception events of the JsonStore? var grid = new Ext.grid.GridPanel({ store: new Ext.data.JsonStore({ listeners: { load: this.onLoadSuccess.crateDelegate(this), exception: this.onLoadException.createDelegate(this) } }), onLoadSuccess: function () { // success }, onLoadException: function () { // error }, } 49. extjs decode() ? var json = Ext.decode(response.responseText); Ext.Msg.alert(‘Error’, json.error); 50. Extjs Vs jQuery: ExtJs and JQuery are kind of apples and oranges. You can compare Ext Core to JQuery, and ExtJs to JQuery UI. Ext JS is a full-fledged widget library while jQuery (not jQuery UI) and Mootools are JavaScript frameworks that help with DOM manipulation etc. Whilst jQuery and Mootools help with the general workings of a site. jQuery UI is a much less rich set of components. Ext JS seems to be focussed on tables and storing Ext JS Questions and Answers pdf Download Read the full article

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rafi1228 · 6 years ago

Link

Get advanced with Node.Js! Learn caching with Redis, speed up through clustering, and add image upload with S3 and Node!

What you’ll learn

Absolutely master the Event Loop and understand each of its stages

Utilize Worker Threads and Clustering to dramatically improve the performance of Node servers

Speed up database queries with caching for MongoDB backed by Redis

Add automated browser testing to your Node server, complete with continuous integration pipeline setup

Apply scalable image and file upload to your app, utilizing AWS S3

Requirements

Basic knowledge of Node, Express, and MongoDB

Strong knowledge of Javascript

Description

Go beyond the basics of Node! This course will give you the skills needed to become a top Node engineer.

Query Caching with Redis? You will learn it. The Node Event Loop? Included. Scalable File Upload? Of course!

——————————

This is a must-take course if you work with Node.

Node Internals: Here’s one of the most common interview questions you’ll face when looking for a Node job: “Can you explain Node’s Event Loop?” There are two types of engineers: those who can describe the Event Loop and those who cannot! This course will ensure that you are incredibly well prepared to answer that most important question. Besides being critical for interviews, knowledge of the Event Loop will give you a better understanding of how Node works internally. Many engineers know not to ‘block’ the Event Loop, but they don’t necessarily understand why. You will be one of the engineers who can clearly articulate the performance profile of Node and its Event Loop.

Caching with Redis: We’ll also supercharge the performance of database queries by implementing caching backed by Redis. No previous experience of Redis is required! Redis is an in-memory data store purpose built for solving caching needs. By adding caching to your application, you can decrease the amount of time that any given request takes, improving the overall response time of your app.

File Upload: There are many resources online that offer suggestions on how to handle file upload, but few show a solution that can truly scale. Hint: saving files directly on your server isn’t a scalable solution! Learn how to leverage AWS S3 to implement file upload that can scale to millions of users with a few dozen lines of simple code. Plentiful discussions are included on security concerns with handling uploads, as well.

Continuous Integration Testing: This is a must have feature for any serious production app. We’ll first learn how to test huge swaths of our codebase with just a few lines of code by using Puppeteer and Jest. After writing many effective tests, we’ll enable continuous integration on Travis CI, a popular – and free – CI platform. Testing can sometimes be boring, so we’ll use this section to brush up on some advanced Javascript techniques, including one of the only legitimate uses of ES2015 Proxies that you’ll ever see!