Learn Chrome, Cypress and D3

Optional chaining ?. in javascript is a new feature introduced in ES2020. Optional chaining changes the way properties are accessed from deeply nested objects. It fixes the problem of having to do multiple null checks when accessing long chain of object properties in javascript.

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.

javascript

Optional Chaining

Imagine the following.

You join a new project and after getting access to the repo you notice that there's no tests.

You decide to ask the team whether they are in different repo or something and unfortunately the answer is:

>We don't have any tests, we didn't have the time.

😐

In this collection we're going to learn how to add e2e tests with cypress.io to an existing React app in order to do two things:

- 🌟 Ensure that our app currently works as intended
- 🌟 Allow us to add features to it with a technique called "Cypress Driven Development" 

In less than 20 minutes we're going to go through:

- ⚡️Adding cypress.io setup to an existing project
- ⚡️Testing search functionality with `data-cy` properties
- ⚡️Using "Cypress Driven Development" to add a new feature to an app
- ⚡️Use Cypress UI to debug an API response
- ⚡️How to use `cy.only` and `cy.skip` in order for us to build our e2e test suite faster

and much more!

Fast, easy and reliable testing for anything that runs in a browser.

cypress

Add e2e tests with cypress to a React application

One of the most important — but most ignored — practices for web developers is performing end-to-end testing on applications before they go live into production. You know: making sure they work like they’re supposed to. But testing can be tedious, and definitely not fun.

In this course, Brett Cassette will show you how you can test all layers of your application stack, simultaneously, with Cypress. When you use Cypress, it’s like having a robot that uses your app the way a real user would. Cypress reports if things work the way you designed them to — and if they don’t — every step of the way. And it’s fun.

After completing this course, you’ll be ready to apply the same E2E testing principles to your own applications. Stop leaning on your QA department (if it exists) to stress-test your application, and ship your app knowing it’s ready. 


Test Production Ready Apps with Cypress

Chrome DevTools are incredibly useful for a frontend developer, sometimes we spend more time using them than our text editor of choice.

That's why it's so important to understand this tool better - those quick lessons will teach you things that will help you to become a more effective developer.

You will learn how to:

- **Use (experimental) CSS Overview to learn all about CSS used on a page in a minute**
- **Style console.log messages with CSS** - a _crucial_ skill for any senior developer (j/k)
- **Debug your code (on production and local environment) with logpoints**
- **Run a Lighthouse audit of your site**
- **Choose accessible colors for your website that have an AAA contrast ratio rating**
- **Force a DOM element state in Chrome DevTools**
- **Use Console utilities to make debugging easier**
- **Copy a network request as fetch or cURL with Chrome DevTools**

Have fun!

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

chrome-devtools

Chrome DevTools tips & tricks

The tools available for unit testing have come a long way. While testing may never be “easy”, the available tools have certainly moved testing closer to the simple end of the spectrum. Full end to end testing hasn’t quite kept the same pace and as a result many applications are testing manually and often by users in production. Cypress provides a testing environment that makes end-to-end testing fast and reliable with a simple API that makes creating automated unit tests for your web applications a no-brainer.


End to End testing with Cypress

In this course we will learn and demonstrate the fundamental concepts and APIs of D3, on our way to building several common chart types. We’ll start with the building blocks upon which all D3 visualizations are built; things like scales, interpolators, and selections. We’ll see how to load data with D3, and how to put its full name, Data Driven Documents, into action. We’ll build column and bar charts, scatter plots, and area charts. Most importantly, we’ll gain an understanding of the conventions and patterns that underlie all D3 projects and examples, enabling you to dissect, understand, and build virtually any D3 visualization on the internet.

D3.js is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG and CSS. D3’s emphasis on web standards gives you the full capabilities of modern browsers without tying yourself to a proprietary framework, combining powerful visualization components and a data-driven approach to DOM manipulation.

Build Interactive JavaScript Charts with D3 v4

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.

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

This course covers D3 v3. If you'd like to learn about v4 of D3 (the latest version) [click here for the course on that](https://egghead.io/courses/build-interactive-javascript-charts-with-d3-v4).

This series will gently guide you through the first steps in getting to know D3. The curve can be steep, but with a few simple tools, you'll be charting your buns off in no time flat.

Use D3 (v3) to Build Interactive Charts with JavaScript

This is a small collection of videos to help you get familiar with Chrome browser's performance oriented developer tools.
In this collection, learn how to record a performance profile, tweak the settings to get the most relevant profile and finally a look into the different sections of the performance data visualisation.

Basics of Chrome's Performance Devtools

Anything related to JavaScript performance

Javascript Performance

Most of D3’s native selection APIs also return the selection (or a new selection), to enable multiple method calls to be chained together. Since the code you write isn’t on the selection prototype, chaining your methods would take some extra work. `selection.call()` will call any function reference you give it, providing the selection as the first parameter, and then it returns the selection for you to ensure chaining is supported.

Better Code Organization with selection.call() with D3 v4

Making SVGs responsive is unfortunately not as simple as adding some media queries. This lesson introduces the `viewBox` attribute, which is used to control how SVGs scale. We’ll also examine a reusable function that can be used to make nearly any visualization responsive.

Make D3 v4 Charts Responsive with the viewBox attribute

In D3, the General Update Pattern is the name given to what happens when a data join is followed by operations on the enter, update, and exit selections. When a chart's data changes over time and each update can both create new elements and destroy existing ones, the General Update pattern can help convey meaning to users. This lesson demonstrates the pattern using animated transitions on a column chart.

Animate with the General Update Pattern in D3 v4

Ensuring your charts are responsive is essential if you want them to work regardless of the user's device and screen size. In this lesson we'll learn how the viewBox attribute of SVG elements works, and apply that knowledge to make a future-proof D3 chart.

Responsive D3 charts with the viewBox attribute

 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

Since D3 outputs standard markup, you can use familiar dev tools and inspectors to debug your visualizations. In this lesson we’ll look at how to use Chrome Dev Tools to examine the data associated with your generated markup and experiment with styles to speed up the development process.

Debug D3 v4 with Dev Tools

D3 makes it easy to add meaningful animations to your data visualizations. Whether it’s fading in new items or tweening existing shapes to display new values, adding transitions is easy. This lesson shows you how to add animations while building on your existing knowledge of D3 selections.

Animate Transitions in D3 v4

Create a line chart, then easily convert it to an area chart

Line and Area Charts with D3

Mapping abstract values to visual representations is what data visualization is all about, and that’s exactly what D3 scales do. This is usually done using pretty straightforward algorithms, but nothing is straightforward when you’re working with Date objects in JavaScript. If you’re plotting temporal data, you need to use a time scale.

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