Learn Angular-cli, Babel and Mocha

npm is the package manager for JavaScript. Find, share, and reuse packages of code from hundreds of thousands of developers — and assemble them in powerful new ways.

We can write our package using the latest JavaScript syntax with a compilation step. In this lesson we will install `babel-cli` and `babel-preset-latest` and wire up a `build` script to compile our code using the babel “latest” preset when source files change. This means those using our package can use it in any version of JavaScript even though we are using the latest syntax for our source code.

Set up compilation of source code using babel with npm scripts

Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework.

chai

Every dependable library needs to have tests to ensure that you don't push accidental bugs. In this lesson, see how you can set up mocha and chai to start testing your library.

Setting up Unit Testing with Mocha and Chai

Now that you've got everything set up with mocha and chai, it's time to actually write tests. In this lesson you'll learn how to use `describe` and `it` to outline your tests and make sure you don't break your library in the future.

Unit Testing with Mocha and Chai

angular-cli

Generating components with the Angular CLI allows for scaffolding applications quickly. Learn what will be generated for you and how to generate quickly with shortcuts in the desired directory.

Generate components with the Angular CLI

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

Getting started with angular development can be difficult, with a lot of moving parts. Allow the Angular CLI to handle those complexities so you can focus on creating great applications.

In this lesson you will learn how to install the Angular CLI from npm, create a new application, serve the new application in the browser and edit it with live-reload.

Install the Angular CLI to Create and Serve an Angular Application

Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple and fun. Mocha tests run serially, allowing for flexible and accurate reporting, while mapping uncaught exceptions to the correct test cases.

mocha

Mocha is a testing framework that provides structure for unit tests. In this lesson, we will be setting up Mocha with npm and npm scripts, writing a "Hello World" unit test, then writing the code to make the test pass (as an example of Test Driven Development (TDD), with the "red-green-refactor" workflow).

JavaScript Testing Fundamentals: Hello world unit test with Mocha (in ES6)

In this lesson, we will use Chai's request method to test our Node application's API responses.
By the end of this lesson, you will know how to:
- install the prerequisites to use mocha and chai in your application
- test for HTTP status response codes
- test for a string of text on a page
- test for a json response and validate the properties of the object
- write tests that not only verify the response of your application, but the behavior as well


Test Node RESTful API with Mocha and Chai

Babel has support for the latest version of JavaScript through syntax transformers. These plugins allow you to use new syntax, right now without waiting for browser support.

babel

What is already a nice workflow using Gulp, Browserify, Watchify & Browsersync to enable auto rebuilds & live browser reloading can be further improved by adding Babelify. A simple wrapper around the popular transpiler Babel, Babelify can ‘transform’ source files as they pass through our stream to enable certain Javascript features not yet available in the Browser or Node. We end the lesson by looking at how to generate & extract sourcemaps using `exorcist`.

Gulp and Browserify - Adding Babel & Source Maps

Writing great ES6 style Promises for Node.js is only half the battle. Your great modules must include tests as well to ensure future iterations don't break them. In this lesson, I show you a simple ES6 Promise in Node.js, then walk you through creating tests in Mocha using chai and chai-as-promised to test both resolve and reject methods.

Testing ES6 Promises in Node.js using Mocha and Chai

In this lesson, you will learn how to verify your API server is returning HTTP 400 responses when clients submit incorrect data. Returning HTTP 400 ensures that your clients are notified of the incorrect usage. Testing for them ensures your API returns errors instead of incorrect responses when supplied with incorrect data.

Test for HTTP 400 responses with Mocha and Chai

Babel is a compiler that lets us right future JavaScript not yet fully in browsers (ES6 / ES2015, ES7 / ES2016, etc) and transpile it back into code that can be used now. We'll walk through installing babel, writing some future JS syntax, transpiling it, and running it in a browser.

**This lesson is out of date and uses an older version of Babel.**

Writing next generation JavaScript with Babel 5 (out of date)

webpack is a tool to build JavaScript modules in your application. To start using webpack from its cli or api, follow the Installation instructions. webpack simplifies your workflow by quickly constructing a dependency graph of your application and bundling them in the right order. webpack can be configured to customise optimisations to your code, to split vendor/css/js code for production, run a development server that hot-reloads your code without page refresh and many such cool features.

webpack

Webpack loaders are how you tell webpack to resolve your dependencies and you can use a loader built for the babel transpiler to easily enable ES6 code in your project. Full sourcemap support is also available using webpack's devtool property.

Webpack Loaders, Source Maps, and ES6

In this lesson we will our `UiModule`, that has a `LayoutComponent`, `HeaderComponent` and `FooterComponent`. 

We generate `UiModule` by running the following command:
```
ng generate module ui --module app
```

This generates the new module and imports it in our `AppModule`.

We'll create the `LayoutComponent` using:
```
ng generate component ui/containers/layout
ng generate component ui/containers/header
ng generate component ui/containers/footer
``` 

We update our `AppRoutingModule` and add this component to our first route to make it visible. 

The `HeaderComponent` and `FooterComponent` are referenced in the LayoutComponent and we implement the actual templates!

Create Application Layout with Components in an Angular CLI Project

In this lesson we will add the `ProductModule`, where our actual application code will live.

```
ng g m product --routing
``` 

We will add 2 routes to `AppRoutingModule`,  the first is a redirect route that redirects any unhandled paths to `products`. The second route is the actual `products` route, that 'lazy-loads' the `ProductModule`.

We use the `ng` command to create the `ProductListComponent` and `ProductDetailComponent`, which are so called 'containers components'.

Container components are responsible for fetching data, handling routes and passing data into the 'presentational components' 

We will add 2 routes to `ProductRoutingModule`,  one to each of our new Container Components.

Lastly we will use  `ActivatedRoute` in `ProductDetailComponent` to fetch the `:id` from the route.

Create Container Components for Retrieving Data in an Angular CLI Project

In this lesson we will create the presentational components for the product list and detail pages. These components define how the data is displayed and are being referenced from the Container components.

The new components are `ProductsComponent` and `ProductComponent`.

After using `ng generate` to generate these components, we will update the `ProductListComponent` to invoke `ProductsComponent` and pass in our local `products` array.

In `ProductsComponent` we loop over each of the items we get from the `@Input() products` and pass each one into our `ProductComponent`.

The `ProductComponent` has 2 `Inputs()`, one for the `Product` and a `boolean` that toggles showing the product details. This is useful because don't want to show product details in the list view.

After the `ProductComponent` is implemented the last step is to reference it from the `ProductDetails` container component. 

Create Presentational Components for Displaying Data in an Angular CLI Project

In this lesson we will create the `ProductsService` that is responsible for the interaction with our API. 

We will inject the `HttpClient` that we get from `@angular/common/http`. To make this working we need to import `HttpClientModule` in our `AppModule`.

We define a `getProducts` and `getProduct` method so we can get a list of products and an single product which we will use in respectively the `ProductList` and `ProductDetail` components. 

In both components we will use the `ngOnInit` lifecycle hook to invoke the methods on the service, and retrieve the data by subscribing to it. 

[Link to product api used in lessons](https://github.com/beeman/egghead-products-api)

Create an Angular Service to Retrieve Data from an API 

In our 'container components' we use the `ngOnInit` lifecycle hook to subscribe to our service. While this works, there is a downside: the components get loaded before the data is available, which results in that we show empty components. This is particularly visible on slow connections.

To fix this we create a `ProductsResolver`, and implement the `resolve` method that fetches the data from the service. In `ProductRoutingModule` we add the `resolve` property to our route, and add make the `ProductsResolver` resolve and store the data in the `products` property.

Inside our `ngOnInit` in `ProductListComponent` we can now subscribe to the route data, which makes the usage of the service in this component obsolete.

We do the same for the `ProductDetailComponent`. After this there are no longer empty components, the router will not navigate after the data is retrieved.

Create Angular Resolvers to retrieve the product data from the Service

In this lesson we will install the latest version of Angular CLI and use the `ng new` command to scaffold out the application.

Scaffold a New Angular App using Angular CLI

In this lesson we will add Bootstrap to our project. This allows us to focus on building our app without having to spend too much time writing custom CSS.

We will use grab the URL too the Bootstrap CSS from [bootstrapcdn.com](https://www.bootstrapcdn.com/)  and add it to our project by adding a `@import url('')` statement to `src/styles.scss`.

Add Bootstrap to an Angular CLI Project

The default Angular CLI configuration generates components that consist of 4 files. The component class, an HTML template, a stylesheet and a spec file that contains the unit test.

In order to keep our components concise we  update our `AppComponent` and move the template and style from an external file to inline. This allows us to delete the 2 external files. 

We can configure our project to generate the template and the style 'inline' by default.

To do this we run the commands:
```
ng config schematics.@schematics/angular.component.inlineStyle true
ng config schematics.@schematics/angular.component.inlineTemplate true
```

The changes are made to `angular.json` in the project root.


Configure Defaults for Generating Code with Angular CLI

A default Angular application ships with two default environment files that can store constants that are different for each environment, one for development and the other for production.

We will define the `apiUrl` constant in both development and production environments. 

The value for development is  `http://localhost:3000/api` and the value for production is `https://egghead-products-api.now.sh/api` .

In `angular.json` we can find a `configurations` object where our `production` build is defined. We can see that in a production build, the `environment.prod.ts` will replace `environment.ts`.

[Link to product api used in lessons](https://github.com/beeman/egghead-products-api)

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