Learn Angular-cli, Puppeteer and Xstream

OpenGraph images are the images you see when you paste a link into a social platform and it "unfurls" into an image, title, and description. This happens on Twitter, Discord, Slack, and many other platforms. This collection goes over everything from designing OpenGraph images in Figma, to implementing them in CodeSandbox, to returning headless browser screenshots from Netlify Functions, and finally using Cloudinary as a write-through cache. 

You will come away from this collection with the ability to ship an API that you can use on any of your sites, and also on-demand, that can generate images for not only OpenGraph unfurls, but also for Instagram, GitHub, and more. Using headless browsers with playwright to generate our images means we get full access to all the responsive power of CSS and all the logical power of JS to handle layout, importing assets like pngs, choosing different fonts, and more.

The image below is generated via the project you'll build and deploy in this course

![An example opengraph image](https://relaxed-payne-d1bfbe.netlify.com/opengraph?title=Building%20an%20OpenGraph%20image%20generation%20API%20with%20Cloudinary%20Netlify%20Functions%20and%20React&tags=figma,netlify%20functions,playwright&author=chrisbiscardi)

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

Building an OpenGraph image generation API with Cloudinary, Netlify Functions, and React

End-to-end testing assures you of a few things: that all the integrated pieces of an application properly function, all those pieces work together as expected, and your tests include and simulate real-user scenarios — something unit and integration tests just don't do.

This course introduces you to two great tools for E2E testing: 

* Puppeteer opens and runs applications in a Chromium browser and performs the actions it's given.
* Jest asserts that the integrated pieces work as expected and that add-on libraries like Faker and pixelmatch take our tests to the next level.

Over 9 lessons, we will create common application features and use Puppeteer and Jest to run different types of tests against them. You'll get practice using these tools to render content, mimic user activity, automate tests, and measure the overall performance of your application.

jest

End to End Testing with Google's Puppeteer and Jest

Puppeteer is a Node library which provides a high-level API to control headless Chrome or Chromium over the DevTools Protocol. It can also be configured to use full (non-headless) Chrome or Chromium.

puppeteer

When taking screenshots, it's important that the browser is big enough to show all of the content in the DOM that we want to screenshot. We can do this by setting the viewport.

Setting the viewport on a Playwright headless browser

Cycle.js is a framework where your app is described as a simple function taking an event stream as input and outputting an event stream.

cycle

This lesson is the first in an introduction to Cycle.js. We will see how to build from scratch a toy version of Cycle.js. See how to use RxJS to create simple web apps, and how to separate logic from effects.

Separate Logic from Effects in Cycle.js

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

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)

Use the Angular CLI Environment to Define Constants

In this lesson we are going to set up our basic app, set our environment variables, define our targeted viewport, and install Jest, Puppeteer, and Faker. We'll use these features to write our end to end tests. 

Setup and Install Dependencies for Testing with Google's Puppeteer

Now that we have our setup and environment ready for using Puppeteer to test our create-react-app, we can write our first tests. We will test our h1 and navigation, to make sure that they load correctly. In this lesson, we will be able to watch puppeteer open up a browser and evaluate our tests in real time. 

Test HTML Content on a Webpage with Puppeteer

In this lesson we are going to test a form submission by replicating keyboard input, mouse clicks, and touchscreen events. This will be done with random user information generated by Faker. We will test this in different contexts, including an iPhone 6 environment.

Replicate User Activity with Faker and Puppeteer

In this lesson we are going to test that a cookie is saved to the document whenever our login form is submitted. Then we will also learn how to set cookies from within our tests. 

Work with Document Cookies in Tests with Puppeteer

In this lesson we are going to write two tests that check our application for any console logs an page errors. We will also learn how we can log these out to our terminal. 

Check for Console Logs and Exceptions with Puppeteer

In this lesson we are going to take a screenshot and a pdf of our application. We'll add this to conditionally run when one of our tests fail. This way we can see what our test was seeing when it failed. These screenshots can help debug why tests fail. 

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