Learn Ember, Linux and Ngrx-store

As your Angular application grows, it becomes more difficult to manage application state.

NgRx can help with that!

In this course, we will learn how to convert an Angular application from using stateful services into using NgRx.

We will accomplish this by adding a new feature, including building a reducer and actions. We'll also touch on using selectors to query our state, managing collections with NgRx entity, async operations, and hiding implementation details with the facade pattern.

Angular is a development platform for creating applications using modern web standards. Angular includes a wealth of essential features such as mobile gestures, animations, filtering, routing, data binding, security, internationalization, and beautiful UI components. It's extremely modular, lightweight, and easy to learn.

angular

Reactive State Management in Angular with ngrx

***Note: RxJS imports have changed since the publication of this course. The concepts being taught on RxJS are still applicable.**

Angular has many built-in features for working closely with RxJS to help you build entirely reactive applications. This course will teach you how to use Angular with RxJS. We will learn how to use the ngrx/store library to manage state in a clean, reactive "Redux style."

This course assumes you've got a working knowledge of Angular and reactive programming with RxJS. If you don't, you might want to watch the following courses to get you up to speed! 
- [Get Started with Angular](https://egghead.io/courses/get-started-with-angular) 
- [Introduction to Reactive Programming with RxJS](
https://egghead.io/series/introduction-to-reactive-programming). 
- [Step by Step Async Programming with RxJS](https://egghead.io/series/step-by-step-async-javascript-with-rxjs) 
- [Getting Started With Redux](https://egghead.io/series/getting-started-with-redux), a course by Redux's, Dan Abramov.

We also have Intermediary Angular courses if you'd like to acquire more in-depth knowledge. 
- [Dependency Injection](https://egghead.io/courses/angular-2-dependency-injection-di-explained
- [Components, Directives](https://egghead.io/courses/building-angular-components)
- [Forms](https://egghead.io/courses/intro-to-angular-forms)
- [Router](https://egghead.io/courses/intro-to-angular-router)
- [Animating Web Apps](https://egghead.io/courses/animate-angular-web-applications)



Build Redux Style Applications with Angular, RxJS, and ngrx/store

Reducers are also often used for changing a single property inside of other reducers. This lesson shows how a type can enter the people reducer, but then the people reducer can use a different type to call the clock reducer and get a value back.

Use a Reducer to Change an Object's Property Inside an Array

This lesson summarizes everything the course has covered and how Angular 2, RxJS, and ngrx/store work together to achive a reactive application.

Review of Angular 2, RxJS, and Reducers from ngrx/store

The scan operator in RxJS is the main key to managing values and states in your stream. Scan behaves just as a reduce function would, but scan is able to collect values from streams over time. This lesson covers using startWith to set the initial accumulator value then using scan to update the value of the clock from the clicks and interval.

Manage State in RxJS with StartWith and Scan

While you have multiple streams flowing into your scan operator, you'll need to map each stream to the specific values you need to update your state the way that you want. This lesson covers using the map operator to determine what the click and interval should do when the state is updated.

Map Streams to Values to Affect State

Angular templates use a special Async pipe to be able to render out Observables. This lesson covers the syntax used to create an Observable in Angular and then to render it out in the template.

https://github.com/johnlindquist/rxjs-in-angular2/tree/11aa4c29a4536dad0ef26b78d8f7f503e4372f74/src

Render an Observable with the Async Pipe

ngrx/store is a library that simplifies common RxJS patterns for managing state and gives you an easy api to use it within your Angular application. This lesson shows how to convert a common startWith and scan stream into an ngrx Store and reducer.

Use ngrx/store and Reducers for Angular Application State

Angular allows you to pass values from inputs simply by referencing them in the template and passing them into your Subject.next() call. This lesson shows you how to make a number input and pass the value so you can configure how much you want the clock to change.

Pass Template Input Values to Reducers

The components inside of your container components can easily accept Observables. You simply define your custom @Input then use the Async pipe when you pass the Observable in. This lesson walks you through the process of passing an Observable into a Component.

Pass Observables into Components with Async Pipe

Reducers can easily be used inside one another to update related state. This lesson shows how you can use the clock reducer inside of the people reducer to create the time for each new person.

Use Two Reducers Together

RxJS allows you to combine streams in various ways. This lesson shows you how to take a click stream and combine it with a store stream to use a value from the store inside a reducer.

Use a Value from the Store in a Reducer

A JavaScript framework for creating ambitious web applications.

ember

In this lesson we will create an `updateContent` method that sets the value of our `content` property to the current epoch timestamp. We need to call `toString()` on the `Date.now()` method in order to make TypeScript happy.

```
updateContent() {
  this.content = Date.now().toString()
}
```

We create a constructor that takes the options parameter, call `super(options)` and call into our `this.updateContent()` method.

```
constructor(options) {
  super(options)
  this.updateContent()
}
```

When we refresh our page we can see that the value of `content` is set to the epoch timestamp. 

To make the content really dynamic we use `setInterval()` to call into `updateContent` each second: `setInterval(() => this.updateContent(), 1000)`.

When we save our file we see that our content does not get updated anymore and when we check the console we see that we get an error telling us that: The 'content' property on the my-component component was changed after it had been rendered. The error also informs us that we should Use the @tracked decorator to mark this as a tracked property.

We add the @tracked decorator to our property, we import tracked from @glimmer/component and we refresh the page. We verify that `content` gets updated each second.

We change our `updateContent` to add our the timestamp to the array. When we use `this.items.push(this.content)` to achieve this we see that the list does not get updated. This is because the `@tracked` decorator only tracks the re-assignment of properties.

The way to get this working is by re-assigning our `items` array inside `updateContent`. We assign a new array, de-structure the current items array and add the new content.

```
this.items = [...this.items, this.content]
```



Use dynamic data in a GlimmerJS component

In this lesson we will use the ember cli to generate a new component. Running `ember g glimmer-component my-component` generates the template and component class. We change the content of our component and add it to the main template in order to show it on the page.

Create a new GlimmerJS component

In this lesson we will add a variable called `content` to our component class, initialize it as a string and display the variable in our class using the double curly braces syntax, which is the handlebars expression for expressions, `{ {content }}`. 

After this we create a new class variable called `items`, initialize it as an array with strings. To display this list in our template we add a `<ul></ul>` and inside this unordered list we use the handlebars `each` helper to display the list items.

And inside our each statement we will print a `<li>` tag and render `{{ item}}` inside it.

```
<ul>
  {{#each items key="@index" as |item| }}
    <li>{{item}}</li> 
  {{/each}}
</ul>
```



Use template variables in a GlimmerJS component

Stores can accept as many reducers as you need. This lesson covers adding a second reducer that will be used to control an array of people.

Add a Second Reducer to the Store

While action types allow you tell your reducer what action it should take, the payload is the data that your reducer will use to update the state. This lesson shows you how to pass an action payload along with your action type to update the state.

Dispatch Action Payloads to Reducers

Instead of simply pushing numbers on a timer into the template, now we'll move on to pushing actual Dates. We'll still use the Async pipe, but we'll also add on the Date pipe with some formatting to display the Date just the way we want it.

Render an Observable Date with the Async and  Date Pipes

A reducer needs to know what you want it to do whenever it's called. You do this by passing along an action type then the reducer can switch based on the type to achieve the logic you need. This lesson covers dispatching action types to your reducer to update the state based on that type.

Dispatch Action Types to Reducers

Observable.merge allows you take two different source streams and use either one of them to make changes to the same state of your data. This lesson shows how you can use a stream of clicks and an interval stream and use either one to update the clock.

Handle Clicks and Intervals Together with Merge

While Angular usually uses event handlers to manage events and RxJS typically uses Observable.fromEvent, a good practice when using Angular and RxJS combined is to use Subjects and push the value through each event so that you can use it as part of your stream.

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