Learn D3, Redux-observable and Svelte

JavaScript community has been shaken recently by a release of Svelte 3 and for a good reason - it's a completely different approach than React or Vue. To quote the docs:

"[Svelte](https://svelte.dev/) is a radical new approach to building user interfaces. Whereas traditional frameworks like React and Vue do the bulk of their work in the browser, Svelte shifts that work into a compile step that happens when you build your app."

**The best part?** If you have 26 spare minutes you can learn the basics of Svelte 3 and start building your own apps with it!

Enjoy!



The magical disappearing UI framework

 - The web's JavaScript bloat crisis, solved. Svelte turns your templates into tiny, framework-less vanilla JavaScript.
 - Simple and familiar. Build apps out of composable, easy-to-write blocks using languages you already know.
 - Super fast, rock solid. Compile-time static analysis ensures the browser does no more work than it needs to.

svelte

Up and running with Svelte 3

Handling async actions that affect your application’s state sounds like a tall order, but Redux makes it possible — and a win-win for you and your app’s users.

In this course, we will begin with nothing more than an empty directory and a text editor. Through small, focused lessons, we’ll learn how to set up a React project that uses Redux for state management and redux-observable for asynchronous actions. We’ll see how ‘epics’ are registered and how they each receive a ‘stream’ of actions from the store.

With an understanding of how things work, we’ll move onto solving common problems like: 
- Ajax cancellation
- creating sequences of async actions
- enabling code reuse through higher-order Observables 
- and much more.

RxJS 5-based middleware for Redux. Compose and cancel async actions to create side effects and more.

redux-observable

Asynchronous State Management with redux-observable v1

***Note: RxJS imports have changed since the publication of this course. Operators now must be passed into `.pipe` to be applied to an observable.***

In this course we will begin with nothing more than an empty directory & a text editor. Through small, focussed lessons we’ll learn how to setup a React project that uses Redux for state management and redux-observable for asynchronous actions. We’ll see how ‘epics’ are registered and how they each receive a ‘stream’ of actions from the store. 

With an understanding of how things work, we’ll move onto solving common problems such as Ajax cancellation, creating sequences of async actions, enabling code reuse through higher-order Observables and much more. 

## **UPDATE:** 
This course is outdated, view updated material here: [Asynchronous State Management with redux-observable v1](https://egghead.io/courses/asynchronous-state-management-with-redux-observable-v1)

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

Up and Running with redux-observable

D3, or Data Driven Documents, is the defacto standard for data visualization on the web. It's an incredibly powerful library that gives you all the tools you need to build just about visualization you can dream of.

D3 is not a collection of predefined charts. Instead, it's a robust set of utilities you can use to ingest and transform data, to map that data to screen values, and ultimately to manipulate the DOM to render your visuals.

When working with React, D3's desire to manipulate the DOM is at odds with React's goal of rendering the UI as a function of state. So how do we handle this? Simply put, we use D3 for everything up to the point where we want to render our output, and then we hand all that data to React for rendering.

In this course, we'll start from scratch and build out an SVG bar chart for some sample data. We'll lean on D3 for its tools and then hand that data off to React for rendering.

Create A Bar Chart with React and D3

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

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

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

Redux is a predictable state container for JavaScript apps.
It helps you write applications that behave consistently, run in different environments (client, server, and native), and are easy to test.

redux

In this lesson we’ll learn exactly what’s needed to incorporate redux-observable into an existing React/Redux application. We’ll learn what ‘Epics’ are, and how they receive a stream of actions and return a stream of actions. In-between is where we get to apply side-effects, call out to external services etc etc. In this lesson we’ll demonstrate the ‘async’ nature of epics by responding to an action with another, delay action.

Add redux-observable to an existing Redux project

In this lesson we’ll learn how to perform an Ajax request to an external API in response to an action in the redux store. We’ll see how, within the epic, we get access to actions after any reducers have been executed and how we can convert that incoming action into a resulting one that will save the data received into the redux store.

Use redux-observable for simple Ajax requests

With redux-observable, we have the power of RxJS at our disposal - this means tasks that would otherwise be complicated and imperative, become simple and declarative. In this lesson we’ll respond to an action by queuing up 2 separate Ajax requests that will execute sequentially. Then we’ll group the results from both into an array and produce a single action from our epic that will save the data into the redux store

Create a queue of Ajax requests with redux-observable and group the results.

When accepting user input and converting it into a request that talks to the outside world, we can often end up in a situation where responses are no longer relevant. This is a common case in type-ahead style input fields - we would only want to call an external search API after the user has stopped typing for a short amount of time. In this lesson we’ll see how we can begin to combine RxJS operators to solve such problems. 

Debounce user input to avoid repeated Ajax requests

Any application that uses external services such as APIs should be able to handle errors gracefully. Often this requires no more that displaying a message to the user and ensuring the application continues to function. In this lesson we’ll look at how we can convert an error from the network into an action that is dispatched into the Redux store, allowing us to show an error message to the user and prevent the application from crashing.

Handle network errors gracefully

Although ‘epics’ in RxJS are often described as ‘actions in, actions out’, there may be times when you need to ‘bail out’ of an action, or to just ignore the current one given some condition. By learning about RxJS’s `filter` Operator, we’ll see how easy it is to do ‘nothing’ when you need to. We’ll also see how the composition techniques available in RXJS allow us to control the UI in a declarative manner.

Filter a stream to exclude empty values

In certain situations, you care more about the final state of the redux store than you do about the particular stream of events coming out of an epic. In this lesson we explore a technique for dispatching actions direction into the store, having the epic execute as they would normally in production, and then assert on the updated store’s state.

Use tests to verify updates to the Redux store

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

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.