 Resources from Mykola Bilokonsky in 2024

In this course we’ll take a deep look at the Elements panel in the chrome devtools. We’ll step through each button and tab on this panel and discuss how to use them to interact with your web application as it runs.

The Chrome Developer Tools (DevTools for short), are a set of web authoring and debugging tools built into Google Chrome.

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Debug the DOM in Chrome with the Devtools Elements Panel

This course examines the Sources panel in the Chrome DevTools, which allows you to see what files are responsible for the various things on the screen. Bundled into this panel, though, is the single most useful tool for any JavaScript developer - the JavaScript Debugger. We’ll use the Debugger to inspect JavaScript as it runs, allowing you to watch (and even interact with) the state of your application as it runs in ways that’ll blow your mind if you’ve mostly used console.log to debug your applications to this point. 

Debug JavaScript in Chrome with DevTool Sources

This course will examine the Network panel in Chrome DevTools. We’ll step through the request log, examining the various properties exposed. We’ll talk about timing, filtering, throttling and generally using the network panel to better understand the ways in which our applications exist within a connected context.

Debug HTTP with Chrome DevTools Network Panel

Most examples for reduce show you how to take an array of numbers and reduce them to a simple sum. Reduce is a great tool for this, but it can do so much more. It is a powerful tool, and essential to functional programming techniques.

This course will dig deep into the Array#reduce in JavaScript and give you a solid understanding to start using it today.

JavaScript® (often shortened to JS) is a lightweight, interpreted, object-oriented language with first-class functions, most known as the scripting language for Web pages, but used in many non-browser environments as well such as node.js or Apache CouchDB. It is a prototype-based, multi-paradigm scripting language that is dynamic, and supports object-oriented, imperative, and functional programming styles.

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Reduce Data with Javascript Array#reduce

If you are developing JavaScript applications you are likely using logging as an integral part of your development process. Did you know that you aren't limited to simple `console.log` statements? Modern browsers give you a lot more logging options to work with!

This course will explore those options and give you some new logging tools for your professional toolbox.

Advanced Logging with the JavaScript Console

Get more mileage from your console output by going beyond mere string logging - log entire introspectable objects, log multiple items in one call, and apply C-Style string substitution to make the console work for you.

Advanced Console Log Arguments

Organize your log output by grouping your logs into collapsable hierarchies using console.group().

Grouping and Nesting Console Log Output

We'll look at using array.reduce to transform an array of strings into an object that counts the occurrence of each string in the array.

Reduce an Array into a Single Object

Learn how to use the reduce function on javascript arrays to transform a list of values into something else. In this introduction we'll be taking a list of numbers and reducing them into a sum.

Transform an Array into a Single Value using Reduce

Learn how two common array functions - map() and filter() - are syntactic sugar for reduce operations. Learn how to use them, how to compose them, and how using reduce can give you a big performance boost over composing filters and maps over a large data set.

Use Reduce to Filter and Map over Large Datasets

Cascading Style Sheets bring order and beauty to our applications.

Learn how to use native CSS transitions to automagically add motion to your application. By specifying a simple transition rule, changes to the values of specific properties can be interpolated over time to give a graceful, polished look and feel to what used to be a jarring and sudden transition.

Introduction to CSS Transitions

Learn a few advanced reduction patterns: flatten allows you to merge a set of arrays into a single array, the dreaded flatmap allows you to convert an array of objects into an array of arrays which then get flattened, and reduceRight allows you to invert the order in which your reducer is applied to your input values.

Learn to Flatten and Flatmap Arrays with Reduce

In this lesson, we will be looking at two common mistakes programmers make when working with `reduce.` We will see why we always need to pass in an initial value for our accumulator as well as return the accumulator.

Avoid Common Mistakes when Working with Reduce

Javascript has first-class functions which means that any function can stored, passed around, and returned just like an Object can. This allows for a lot of flexibility with how you call functions. This allows us to use array reduction to create functional pipelines by composing arrays of functions.

Compose Functions with Reduce

 AJAX allows us to send requests to the server from our javascript applications, rather than allowing the browser to directly request declaratively specified resources. Under the hood, though, AJAX requests are still just HTTP requests - and that means we can use the Network Panel in Chrome’s DevTools to inspect our AJAX operations!


Examine AJAX Requests with Chrome Devtools

To understand the Network DevTool, you have to understand what HTTP is and how it works. Let’s use the Network DevTool to inspect an HTTP request and its corresponding response so that we can understand what the browser is doing.

Analyze HTTP Requests and Responses with Chrome Devtools

Go beyond console.log by learning about log levels, filtering log output and structuring your output to be meaningful and concise. The JavaScript console object offers many methods to make your life easier - start learning them here!

Log Levels and Semantic Methods

Learn about console.assert, which is syntactic sugar for logging an error the console when a given condition is not met. It's useful, but may not do what you expect if you're coming from another language - watch this lesson to learn how to use it, and when not to.

Proper use of console.assert in JavaScript

Most of today’s websites use optimized, compiled, minified and obfuscated javascript and CSS. Examining this stuff here has some severely limited utility, which is why when developing we rely on sourcemaps. We’ll set up a webpack workflow that uses sourcemaps to show you how they can help your debugging!

Unbundle your JavaScript with Source Maps in Chrome DevTools

Sometimes we need to turn arrays into new values in ways that can't be done purely by passing an accumulator along with no knowledge about its context. Learn how to reduce an array of numbers into its mathematical mean in a single reduce step by using the optional `index` and `array` reducer arguments.

Use the Optional Reduce Arguments

A common problem when dealing with some kinds of data is that not every object has the same nested structure. luke_skywalker.parents.father.is_jedi works, but anakin_skywalker.parents.father.is_jedi throws an exception, because anakin_skywalker.parents.father is undefined. But we can reduce a path to provide safe default values and avoid exceptions when walking the same path on non-homogenous objects - watch to learn how! :)

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mykola bilokonsky