Learn Canvas, Puppeteer and Sequelize

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

A <canvas> element provides scripts with a resolution-dependent bitmap canvas, which can be used for rendering graphs, game graphics, or other visual images on the fly.

canvas

The `canvas` element exposes a 2d context which allows you to draw lines using the `moveTo`, `lineTo`, and `stroke` api. You can combine this with Mouse events to make a simple drawing app.

Draw with Your Mouse on an HTML Canvas

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

Learn some of the different ways you can affect the graphical content that you are drawing to a canvas. We'll cover global alpha, global composite operations and shadows.

Canvas Effects

With the HTML `canvas` you can easily draw text as well as graphics. Let's take a look at basic text manipulation on the canvas.

Drawing Text on Canvas

In this lesson, we cover several different ways to animate graphics drawn to Canvas.

Animating with Canvas

When drawing on the HTML5 canvas element, your fills aren't limited to flat colors. You can use gradients to get smoothly blended color fills on your drawn elements.

Gradient Fills on the HTML5 Canvas

Transformations can change the default canvas coordinate system and create complex drawings with much less code.

Canvas Transformations

In this lesson, listening for and handling mouse and keyboard events in Canvas is covered.

Listening for Mouse and Keyboard Events with HTML Canvas

The HTML Canvas element allows us to access powerful drawing APIs from JavaScript. In this lesson, the first in a series, we will learn about `<canvas>`, and get ready to start drawing.

Introduction to the HTML Canvas element

Now that we have an HTML5 canvas to draw on, let's take a look at drawing simple lines and rectangles with JavaScript

Drawing Paths - Lines and Rectangles

When drawing on your HTML canvas in JavaScript, you aren't restricted to straight lines. Using curves and arcs you are able to create smooth curved lines.

Drawing Paths - Curves and Arcs

You aren't limited to boring black lines when drawing on the HTML5 canvas element. Using styles, you can program interesting colorful images with JavaScript.

Drawing Styles on HTML5 Canvas

In this lesson, you'll learn how to read and write individual pixel color values from a canvas.

Canvas and Pixels

In addition to vector drawing, you can draw bitmap images into a canvas, and also retrieve a bitmap based on the content in a canvas.

HTML Canvas and Images

Sequelize is a promise-based ORM for Node.js and io.js. It supports the dialects PostgreSQL, MySQL, MariaDB, SQLite and MSSQL and features solid transaction support, relations, read replication and more.

sequelize

Sequelize attribute getters and setters are a convenient way to encapsulate extra logic for model properties. In this video, we'll cover adding getters and setters to enhance and even virtualize a column.

Sequelize: Getters, Setters and Virtual Columns

Models in the Node.js ORM, Sequelize, can be expanded with both class level and instance level functions. This video will show you how to extend your models to add helpers or business logic, and explain the methods execution scope.

Sequelize: Class & Instance Methods

Javascript and database systems tend to be at odds with regard to how tables and columns should be named. Sequlize provides all the tools necessary to satisfy naming conventions in both your Node.js code and in your SQL database.

Sequelize: Model & Column Casing

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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