Learn Ember, Immutable and Nightmare

Ember is a javascript framework that provides a rich set of tools for building modern web applications. Unlike many frameworks, Ember comes with opinions and a way of doing things so you aren't left with a ton of decisions to make about problems that have already been solved very well. Ember was designed from the start to deliver a productive and comfortable experience for you, the developer.

In this course you will learn what you need to know to get started building your own Ember we applications. From the absolute essentials like creating a new project with the Ember-CLI tools, templating, routing, and reusable components.



A JavaScript framework for creating ambitious web applications.

ember

Ember 2 Fundamentals

im·mu·ta·ble i(m)ˈmyo͞odəb(ə)l/ adjective - **unchanging over time or unable to be changed**.

Mutating data is the source of never ending headaches in software systems, and JavaScript code is no exception. Immutable data structures, pure functions, uni-directional data flow... you've probably been hearing these terms.

Immutable.js provides us the data structures and utilities that we need to start introducing this powerful concept of immutability into our applications.

Immutable.js provides many Persistent Immutable data structures including: List, Stack, Map, OrderedMap, Set, OrderedSet and Record.

immutable

Learn how to use Immutable.js

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.

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Sometimes our update logic is asynchronous. In this lesson we will investigate two ways in which we can write asynchronous update logic. 

…But, we will also discuss why asynchronous producers should be avoided, and how that can be done by better separating our logic. 

This lesson also demonstrates the “createDraft” and “finishDraft” APIs

Write Asynchronous Producers in Immer and Why You Shouldn’t

In this lesson we will send patches over a WebSocket to our server, and distribute them again from there.

Create a Simple WebSocket Server to Distribute Patches from Immer

Components in Ember are great for reusing code throughout our application. We’ll see how each instance of an Ember component has isolated state and we can over ride as well as set default values.

In this lesson, we will learn how to make a simple, reusable component within an Ember application.

Create Simple Components in Ember

In this lesson, we learn how to create nested routes and templates in an Ember.js application, in addition to how to create nested routes and isolated templates.

Creating nested routes in Ember.js

In this lesson, we will learn how templates work within Ember and how to use HTMLBars. This lesson will cover the connection between controllers and templates and how to use actions within templates as well.

Ember Templating with HTMLBars

In this lesson, we will learn how to install Ember Inspector and use it to see the state of our application and debug it.

The Ember Inspector can be installed from the [Chrome Web Store](https://chrome.google.com/webstore/detail/ember-inspector/bmdblncegkenkacieihfhpjfppoconhi). We will see how the inspector gives us access to information such as the routes available to us, the components used in a particular view, and data that is exposed to us etc.


Debug Ember Applications using Ember Inspector

Immutable.js offers methods to break  immutable structures into subsets much like Array--for instance it has the all powerful slice()--and unlike Array it offers functional methods like take() and skip(). You get the best of both the imperative and functional worlds.

Working with Subsets of an Immutable.js Map()

Equality checking deeply nested objects is painful. Fortunately Immutable.js makes this task easy with its .is() and .isSubset() methods. Let's see how we can take two different Immutable Maps() and check for equality.

Equality Checking with .is() and More

Immutable.js offers the fromJS() method to build immutable structures from objects and array. Objects are converted into maps. Arrays are converted into lists. The fromJS() method can also take a reviver function for custom conversions.

Using fromJS() to Convert Plain JavaScript Objects into Immutable Data

Understanding Immutable.js's Map() and List() structures will likely take you as far as you want to go with immutable programming. They have only small semantic differences between each other and the remaining structures in the Immutable.js family. Sequence, however, has one major difference: it's lazy--which opens a new realm of functional possibilities. Let's write a simple sequence to start.

Exploring Sequences and Range() in Immutable.js

Immutable.js iterables offer the reduce() method, a powerful and often misunderstood functional operator on which map(), filter(), groupBy(), etc. are built. The concept is simple: reduce transforms your iterable into something else, that's all. The name is misleading as you may or may not actually "reduce" anything. Let's replicate the groupBy() and filter() methods with reduce to illustrate how it works.

Transforming Immutable Data with Reduce

While Immutable.js offers .is() to confirm value equality between iterables it comes at the cost of referencing each key and value in both objects. For lightning fast equality checks, Immutable.js can produce a hash code based on an iterable's content. If two iterables have the same content, their hash codes will be the same. It's worth noting that this technique is unsuitable for mission critical application development since there is a chance, however slight, that checksums like these might collide. This is outlined here: https://en.wikipedia.org/wiki/Collision_(computer_science)

Lightning Fast Immutable.js Equality Checks with Hash Codes

The Immutable.js Record() allows you to model your immutable data much like you would model data with native Javascript classes or objects. It differs from native classes because it cannot be mutated after it's creation and it *always* has a default value. It's an excellent construct in which to piece together your stores, be them Flux or some other storage implementation. Let's quickly create an Immutable Record().

Immutable.Record() as data models

In Ember.js, functions that are executed through user interaction with your application are called actions, which can be defined at the route, controller, or component level. In this tutorial, we look at a simple example of defining actions on the controller and hooking it up to our template in order to update properties on the controller.

Add user interaction to Ember.js apps using actions

We will learn how to install Ember-CLI and use it to create a new Ember project. We will also learn how to run the Ember project.

Create an Ember Project with the Ember-CLI

In this lesson, we show how to specify a model for an Ember Route so its data can be displayed. 

Define Models for Routes in 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 learn how to define routes within an Ember application and how to use them to navigate around your application. This lesson will cover the basics of routes and how we can use nested routes to display multiple templates at the same time. We can also cover redirect routes and manually forcing transitions through actions.

Define Routes in Ember 2.0 using Ember-CLI

Immutable.js's Map doesn't promise iteration order after a set() operation. When we need a guarantee for iteration order, we can use OrderedMap. This comes at a slight performance cost, or for you computer science people, it is amortized at an unstable O(log32 N). Let's explore ordering. 

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