Learn Flow, Leaflet and Redux-observable

If you've ever worked on a website for a business, there's a good chance you've included a map.

A Google Map embed is sufficient for showing a location, but doesn't leave you many customization options.

React Leaflet to the rescue!

In this course, Colby Fayock will guide you through a series of lessons and challenges that will build your map making skills as you build out a web app for a fictional restaurant.

You'll get practice with handling API keys and using React Hooks to implement a custom interactive map complete with metadata and additional overlays.

This course has built-in challenges that you are encouraged to pause and work through, but feel free to just watch.

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

Build Maps with React Leaflet

In this collection, you'll learn the basics of creating a new map in your React application with React Leaflet. We'll walk through adding the map itself as well as adding markers with popups, different shapes, and increasingly complex features to your map!

Mapping with React Leaflet

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)

Up and Running with redux-observable

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

In this lesson, you will learn how to add a map to your React application using React Leaflet. We will walk through importing and configuring the Map and TileLayer components from React Leaflet to set up the new map.

Create a New Map using React Leaflet

In this lesson, you will learn how to add a Marker and Popup component to a Map when using React Leaflet. We'll walk you through importing the components and adding each one to the Map. Additionally, we'll resolve an issue with loading marker images that's inherent to creating a new React Leaflet map in Create React App, which we'll fix by manually importing the image from Leaflet and configuring those images to the marker.

Add a React Leaflet Marker with a Popup to a Map

In this lesson, you will learn how to add the Polygon and Circle shape components to a Map when using React Leaflet. We'll walk you through importing both components, adding each component to the Map, and setting a unique color for each shape.

Add Shapes to a Map in React Leaflet

In this lesson, you will learn how to use React hooks to interface with the Leaflet Map API in React Leaflet. We'll connect a ref to our Map component using the useRef hook and then use the useEffect hook to access that ref, find our Map instance, and use it to fly to a new location.

[More details on the Leaflet Map API](https://leafletjs.com/reference-1.6.0.html#map)

Interface with the React Leaflet Map API with the useRef and useEffect React Hooks

In this lesson, you'll learn how to style shapes on your map to change the look and feel using React Leaflet's API. We'll use React component props like color and weight on our shapes to change the colors and styles.

Style React Leaflet Shapes using Component Props

In this lesson, you'll learn how to use CSS to style and animate shapes on your React Leaflet map. We'll use the className prop to add a custom class and add CSS to customize our shapes.

Style and Animate a React Leaflet Shape with Custom CSS

In this lesson, you learn how to use the React Leaflet ZoomControl component to add a custom zoom control to your map. We'll walk through removing the default control to avoid duplicates, using the ZoomControl position prop to change its location, and setting custom icons with the zoomInText and zoomOutText props.

Change the React Leaflet Map ZoomControl Location and Icons

In this lesson, you will learn how to add GeoJSON data to a map in React Leaflet. Using the National Parks in the United States, we'll import a GeoJSON document, create a new Leaflet GeoJSON instance, and add a marker with a popup for each park.

[Parks Locations Example](https://www.nps.gov/maps/tools/npmap.js/examples/geojson-layer/)
[Parks GeoJSON](https://www.nps.gov/lib/npmap.js/4.0.0/examples/data/national-parks.geojson)

Add GeoJSON Location Data to a Map Using Markers and Popups in React Leaflet

In this lesson, we'll add a new tile service as our basemap in React Leaflet. Using the NASA GIBS Blue Marble, we'll update the TileLayer component's url and attribution props to the new service. We'll also add the maxNativeZoom prop which allows us to configure the maximum zoom allowable for the service.

[More info about NASA GIBS imagery](https://earthdata.nasa.gov/eosdis/science-system-description/eosdis-components/gibs)
[GIBS Imagery API](https://wiki.earthdata.nasa.gov/display/GIBS/GIBS+Available+Imagery+Products)

### NASA GIBS Blue Marble Tile Server
Endpoint: https://gibs-{s}.earthdata.nasa.gov/wmts/epsg3857/best/BlueMarble_ShadedRelief_Bathymetry/default//EPSG3857_500m/{z}/{y}/{x}.jpeg
Attribution: NASA Blue Marble, image service by OpenGeo

Change the Map Tile Service of a React Leaflet TileLayer Basemap to NASA GIBS Blue Marble

In this lesson, we'll add a LayersControl toggle to allow us to change between multiple TileLayer basemaps in React Leaflet. Using the NASA GIBS Blue Marble, we'll add an additional TileLayer component, wrap our two TileLayers in BaseLayer components, and wrap all of our layers in a LayersControl to toggle our basemaps.

[More info about NASA GIBS imagery](https://earthdata.nasa.gov/eosdis/science-system-description/eosdis-components/gibs)
[GIBS Imagery API](https://wiki.earthdata.nasa.gov/display/GIBS/GIBS+Available+Imagery+Products)

### NASA GIBS Blue Marble Tile Server
Endpoint: https://gibs-{s}.earthdata.nasa.gov/wmts/epsg3857/best/BlueMarble_ShadedRelief_Bathymetry/default//EPSG3857_500m/{z}/{y}/{x}.jpeg
Attribution: &copy; NASA Blue Marble, image service by OpenGeo

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