Learn Electron, 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

Electron is a framework that makes it easy to create cross-platform desktop apps with JavaScript, HTML, and CSS. Electron and open-source tools give you everything you need to create a compelling desktop app--native user interface elements like menus and dialogs, installers, auto-updates, and more. 

This course will teach you the core concepts of Electron so that you can leverage it to create your own desktop application for macOS and Windows. 

We'll go over:
- Creating user interfaces in Electron (both HTML based and native)
- Understanding Electron's multi-process architecture 
- Shipping your app to users

Electron is a framework for creating native applications with web technologies like JavaScript, HTML, and CSS.

electron

Build a desktop application with Electron

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

In this lesson we’ll load javascript into the BrowserWindow and display the Electron version on the page. Loading javascript into Electron is almost exactly the same as loading it into the browser, however it is a best practice to use the `require` syntax.

Load JavaScript in an Electron BrowserWindow

A main menu is a hallmark of native desktop applications. Electron makes it easy to create native menus and menu items in JavaScript.

We’ll go over creating a menu template using `Menu.buildFromTemplate` and then setting it as the main application menu via `Menu.setApplicationMenu`. 

Create a native desktop system menu with the Electron Menu module

In this lesson we'll learn about `dialog.showMessageBox` . This is the most basic Electron dialog but it offers lots of customization options, such as `type`, `icon`, `title`, and `buttons`. Some of these options vary by platform, so we'll also look at how things differ between Windows and Mac. 

Display native desktop dialog windows with Electron

In this video, we'll learn how to save and open a file using native dialogs in Electron. First, we'll use `dialog.showSaveDialog` to display a native save dialog and use `dialog.showErrorBox` to display an error message if the save failed. Then, we'll open the file we saved using `dialog.showOpenDialog`. Finally, we'll look at how these dialogs look on Windows vs Mac.

Save/Open a file with an Electron dialog window

Dealing with multiple processes in an application is new for many JavaScript developers. We’ll go over what exactly a process is and what the primary responsibilities of the main and renderer processes are. The main process is primarily responsible for creating native UI elements and managing the application lifecycle, while the renderer process runs the HTML based UI. Accordingly, different APIs are available in each process. 

Understand Electron’s main and renderer process architecture

In Electron, we often need to coordinate actions between multiple processes. For example, if a user clicks a button in a renderer process that makes a new `browserWindow` open, we need to be able to send a message to the main process that triggers this action. We’ll look at how to do just that using the `ipcRenderer` and `ipcMain` modules.

Communicate between Electron processes using IPC

`remote` allows you to seamlessly interact with main process modules as if they were in the renderer process. It’s a super useful abstraction over IPC. We’ll learn how to use it and how to avoid some potential gotchas it has. 

[Devtron](https://electron.atom.io/devtron/) is a devtools extension that the Electron team has made. We’ll be using it to view all of the IPC that happens in our application. In this lesson we’ll learn how to include and use it in our code. 

Communicate between Electron processes using the remote module

Every Electron application needs a custom icon. Mac needs an `icns` file and Windows needs an `ico` file. We'll learn how to use a npm module, `electron-icon-maker`, that takes a 1024x1024 PNG and then outputs all the files we need. 

Create an icon for your Electron app

We’ve been running our app in a development environment using the Electron executable. Now let’s learn how to package our app into a `.app` or `.exe` file so that we can distribute it to other users. Electron doesn't provide this functionality out of the box, so we'll use a popular and easy-to-use npm package called [electron-builder](https://github.com/electron-userland/electron-builder) to handle the details. electron-builder will automatically grab our `.ico` or `.icns` file and use that as our app's icon. 

Package your Electron application into a executable file with electron-builder

Code signing ensures that your app was created and distributed by you or your company and has not been modified since it was built. It is done via a special code signing certificate issued by a trusted authority. While you can distribute your Electron app without signing it; code signing is a security best practice and is a prerequisite to implementing auto-updates in your app. We’ll walkthrough how to integrate code signing into your electron-builder build process, what happens when you don't sign your application, and how to verify it's been signed correctly. 

This lesson assumes that you have already purchased code signing certificates from Apple and one of Microsoft's trusted vendors and have exported the certificate as a `p12` or `pfx` file. 

Code sign your Electron application with electron-builder

Once users are using your app, you need a way to ship new features and fixes to them. In this lesson, we’ll learn how to implement auto-updates in your app, which allows you to distribute updates to your application seamlessly. We'll go over how to integrate with Electron's `autoUpdater` module to check for an update and display a prompt to update once it's been downloaded. For our server side implementation we'll just use a plain file server to keep things simple. 


Ship updates to your Electron app with `autoUpdater` (Mac)

In this lesson, we'll go over a few differences in implementing auto-updates on Windows like handling `Squirrel.Windows` startup events and configuring `electron-builder` to build for a `Squirrel.Windows` target.

Ship updates to your Electron app with `autoUpdater` (Windows)

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

Take the first step in learning how to create native desktop applications with Electron. We'll set up a package.json, create an npm start script to launch our app in development, and create a browser window and load a local HTML file into it.

An important concept to understand about Electron is it's multi-process architecture. The main process creates web pages by creating `BrowserWindow` instances, manages application lifecycle events, and more. Each `BrowserWindow` instance runs the web page in its own renderer process. 

Create a "Hello World" app using Electron

In this lesson we'll learn how to load CSS in an Electron BrowserWindow, which is just like loading CSS into the browser. We’ll also use the `ready-to-show` event to only display our BrowserWindow when its rendering is complete.

Load CSS in a Electron BrowserWindow

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. 

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