Learn Chrome, Reason and Xstream

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

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

This course foremost will teach you about the syntax and semantics of the programming language Reason or also referred to as ReasonML. In addition, the course touches on best practices recommended by the official documentation. Each lesson is focusing on a specific feature, concept or best practice and can be watched independently. Still, the whole course is carefully crafted, and each lesson builds up on the previous ones.

Simple, fast & type safe code that leverages the JavaScript & OCaml ecosystems.

reason

Get Started with Reason

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

Node.js is a well established server runtime that many companies are using worldwide. Express.js is a server framework for Node.js used by over 5 million projects. ReasonML is a type-safe functional language that compiles to Javascript.

This playlist collects the basic pieces of information a programmer needs to get started building servers in ReasonML on Node.js and Express.js. Follow along to learn how to get the speed of Node, combined with the added type-safety of Reason.

Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.

node

Making an HTTP server in ReasonML on top of Node.js

Ongoing playlist.

Don't be afraid to watch videos at 1.25x if the pace is too slow!

ReasonML Applications for the React Developer

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

ASP.NET is an open source web framework for building modern web apps and services with .NET. ASP.NET creates websites based on HTML5, CSS, and JavaScript that are simple, fast, and can scale to millions of users.

asp-net

ASP.NET Core SignalR can push events from the server into your Client Application. In this video we will build a client side Todo app with Angular which consumes events from a ASP.NET Core SignalR backend to see how we can consume and synchronize data between our client side Angular Applications.

Consume ASP.NET Core SignalR values in an Angular Application

React is one of the web’s most popular frameworks for building JavaScript applications. 

If you know what you’re doing, React can drastically simplify how you build, use, and maintain code.

Whether you’re a React newbie or you’re ready for advanced techniques, you can level-up with egghead. Explore our in-depth courses, lessons, and community resources to build more powerful applications and crack open your career.

react

Throughout the last year, the use of React hooks has taken the world of web development. Hooks provide users with an easy way to handle interactivity within ReactJS applications, so it's no surprise that the latest release of the ReasonReact library makes great use of them. 

In this lesson, we'll get started using ReasonReact `0.7.x` by scaffolding out an application using the [BuckleScript](https://bucklescript.github.io/) command-line tool. Once scaffolded, we'll go through the steps needed in order to properly run our application within a development environment that is ripe for productivity!

### Resources
* [ReasonML Docs](https://reasonml.github.io/docs/)
* [ReasoNReact Docs](https://reasonml.github.io/reason-react/en/)
* [BuckleScript Docs](https://bucklescript.github.io/)

Up and Running with React Hooks inside of a ReasonML 

Any React developer will agree that 2019 was the year of that hooks took the library by storm. Luckily for us, the ReasonRect library makes it possible to hooks within the context of a ReasonML application.

In this lesson we will take a test drive of the `useReducer` hook within a ReasonML application. By the end, we'll have learned how to define our actions using variants, use records to shape our state, and more!

### Resources
* [ReasonReact Docs] (https://reasonml.github.io/reason-react/en/)
* [ReasonReact Blog - Support for hooks in 0.7.0 Release](https://reasonml.github.io/reason-react/blog/2019/04/10/react-hooks)



Use ReasonMLs Variant & Record types with ReasonReact's useReducer hook to Manage State

When working with traditional React, we often pass functional stateless components the `props` object as an argument. Although there are a few minor differences when working in the context of Reason, the act of passing `props` to a component is done in an extremely similar manner.

In this lesson, we will get a first-hand look at just how similar these processes are by walking through the steps of creating a React Component in ReasonReact. By the end, you'll have developed an understanding of ReasonReact's "named args" syntax which it uses for creating components and you'll have created a re-usable Layout component that can be used to share layout throughout an application.

### Documentation
* [ReasonReact Homepage](https://reasonml.github.io/reason-react/)
* [ReasonReact Docs - Components](https://reasonml.github.io/reason-react/docs/en/components)


Create a Layout Component for Displaying Child Components Inside of a ReasonReact App

One of the key benefits of BuckleScript is the ease in which it makes the process of porting JavaScript libraries so they can be used within the context of a ReasonML application. The Reason Package Index, or [redex](https://redex.github.io/), provides a central place for browsing all available packages. Additionally, creating your own BuckleScript bindings is a straight forward process that also provides value in the form of knowledge surrounding the inner-workings of the library at hand.

In this lesson, we learn how to integrate the emotion css-in-js libray into our project by installing the `bs-css` package. Once installed, we'll create a `.re` file for our style rules and see how we can add global css, as well as styles for specific css classes which we'll target using React's `className` prop.

### Link
* [ReasonReact Docs](https://reasonml.github.io/reason-react/docs)
* [`bs-css` - GitHub](https://github.com/SentiaAnalytics/bs-css)
* [`bs-css` - Redex](https://redex.github.io/package/bs-css)


Implement a Sticky Footer within a ReasonReact App Using the bs-css BuckleScript Package

The axe browser extension (for Chrome and Firefox) is an immensely helpful tool for auditing web pages for accessibility defects.  This extension is powered by the same rules engine developed by Deque Labs in their axe-core open source library which also powers the react-axe development tool.  Each reported defect offers a ton of information about the defect, why it's a problem, severity level, groups impacted and ways to fix the defect.  This can be a great resource for learning more about how to write accessible code.

## Resources
* [Chrome browser extension](https://chrome.google.com/webstore/detail/axe-web-accessibility-tes/lhdoppojpmngadmnindnejefpokejbdd)
* [Firefox browser extension](https://addons.mozilla.org/en-US/firefox/addon/axe-devtools/)

Use the axe Browser Extension to Audit a Web Page for Accessibility Issues

ReasonML is a fantastic way to write Javascript! But it doesn't yet have a built-in async / await syntax. Furthermore the built-in libraries for working with Javascript promises are awkward to work with, and produce code that's hard to read. This lesson will teach the viewer how to use the "bs-let" language extension (called a PPX) to achieve readable, easy to write promise-based code.

Async / Await in ReasonML

Although ReasonML has built-in libraries for working with JSON, they are low-level and difficult to use by hand. The Decco library offers automatically generated JSON decoders, and produce a result that keeps the programmer safe at runtime by telling them whether the data they got matched the shape of the data they expected. 

Automatically decode JSON into records in ReasonML using Decco

WAI-ARIA, the Accessible Rich Internet Applications Suite, defines a way to make Web content and Web applications more accessible to people with disabilities. It especially helps with dynamic content and advanced user interface controls developed with Ajax, HTML, JavaScript, and related technologies. 

aria

tota11y is a great tool to add to your accessibility auditing toolkit.  tota11y is a browser extension available for Chrome and Firefox that helps visualize accessibility violations (and successes), while educating on best practices.  It can make for a really helpful supplement to other accessibility auditing tools.

## Resources
* [About tota11y](https://khan.github.io/tota11y/)
* [Chrome browser extension](https://chrome.google.com/webstore/detail/tota11y-plugin-from-khan/oedofneiplgibimfkccchnimiadcmhpe?hl=en)
* [Firefox browser extension](https://addons.mozilla.org/en-US/firefox/addon/tota11y-accessibility-toolkit/)

Use tota11y to Visualize Accessibility Issues

A modern web browser owned and maintained by Google.

chrome

It's very important to experience our web applications using the tools and techniques that our users are using. Many of our users out there may have vision impairments and may use tools to help them see better. Learn how to use a High Contrast browser extension to see your web application the way many of your users may be seeing it.  You may discover that a lack of contrast between foreground and background colors will cause things to be hard to see or even invisible in certain High Contrast tool settings.

## Resources
* [Chrome browser extension](https://chrome.google.com/webstore/detail/high-contrast/djcfdncoelnlbldjfhinnjlhdjlikmph)

Use a High Contrast Browser Extension to Find Color Contrast Accessibility Issues

screen-reader

We can find issues with heading levels by utilizing our accessibility auditing tools.  The library react-axe, as well as the browser extension axe, will report any findings concerning heading levels.  The browser extension tota11y will annotate all heading levels on a page and show any in red that have issues.  Finally, we can check the Rotor in VoiceOver in Safari.  The Rotor should have a Headings menu and will list in order all of them that are found on the page.  If headings are missing or inappropriate this will help us find them as well.

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