Learn Go, Mocha and Serverless

Starting from a prebuilt frontend, Jason Lengstorf guides you through the creation of a "Corgi Up-boop App" that uses Netlify Functions and Hasura. You can view [the deployed final product on Netlify](https://egghead-serverless-functions.netlify.app/).

You'll set up the Netlify CLI, and configure a local development environment before writing and deploying functions with a few different use cases.

The first example function bypasses CORS restrictions to retrieve corgi data from an example third-party API.

Next, you'll configure environmental variables to securely communicate with the Unsplash API without exposing private keys to the client.

Serverless functions don't persist data by themselves, so we will use  Hasura to create a GraphQL API for tracking the number of "boops" each corgi receives.

This course is an excellent illustration of the speed of Serverless functions, and how fast you can implement functionality in your web applications.

An all-in-one workflow that combines global deployment, continuous integration, and automatic HTTPS.

netlify

Build a Corgi Up-boop Web App with Netlify Serverless Functions and Hasura

Go is a server-side language, but today we can compile Go code to WebAssembly as well - making it possible for us to bring programs written in minimalistic Go code into the browser!

With this collection, we will learn how to compile and run Go WebAssembly programs in Node.js and the browser, and how our Go code can interop with JavaScript and manipulate the DOM. We will also talk about configuring our VS Code workspace and optimizing the Go WASM binary size.

Go is an open-source programming language that makes it easy to build simple, reliable, and efficient software.

WebAssembly with the Go Language

This collection of lessons will cover a variety of topics that teach you how to work with slices and arrays in go. You'll learn how to declare them, create them using literal syntax, iterate over them, add to them, remove from them and other useful things.

Learn about slices and arrays in Go

Create a serverless application and deploy it in under thirty minutes!

We'll be using Netlify, Vite, TypeScript, and React in our project. This stack synergizes extremely well for rapidly developing professional-quality applications. 

If you haven't heard of Vite, it's the French word for quick! It's also a build tool that consists of a dev-server and an extremely fast bundler. It makes for a rapid development loop.

As for the rest. Netlify makes hosting fast and easy with serverless functions and continuous deployment. React enables you to quickly create reusable components. And TypeScript helps you write cleaner code that is easier to refactor. 

So get started and learn how to use this stack in your own applications!

Deploy a Serverless API React Application with TypeScript

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

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

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

Golang has no built-in function(s) to filter an array. This lesson will teach you two different ways to filter.

The first is to create a separate array and add the filtered elements to it. This works great, but doesn't use memory as efficiently as the second way.

The second way shows you how to filter by altering the original array in place without making another array to hold the filtered elements. But, it has a side-effect that I'll tell you about which may help you decide which approach you will use to filter your array. 

Filter an Array in Go

There are numerous ways that you can declare and create arrays and slices in Go. This lesson will show you several and I talk about the advantages and disadvantages of one over another. After watching, you will better understand all of the possible ways you can declare/create as well as the idiomatic way.

These include:

* var
* the built-in function *new*
* the built-in function *make*
* Array and Slice literals

While it is not the main intent of this lesson, I do touch on some of the differences between slices and arrays.

Checkout the code in my [github repo](https://github.com/JeffBNimble/GoLessons/tree/master/Array-Declare).

Declare Arrays and Slices in Go

Go has a special indexing syntax that forms the basis of removing one or more elements from a slice. I will teach you this syntax and show you its various forms.

Based upon that, I'll show you how to remove a single element from a slice. However, you may find this somewhat limiting. I also will show you a more typical example of removing elements from a slice as we iterate over it. This technique shows you how to remove multiple elements from a slice.

Remove Elements from a slice in Go

There is a built-in append function that is used to append elements to a slice. We'll see in this lesson that the append function works only with slices, not arrays. There are also some nifty alternate uses of the the append function that make appending super easy.

Checkout the sample code in my [github repo](https://github.com/JeffBNimble/GoLessons/tree/master/Array-Add).

Append Elements to a Slice in Go

There are a couple of different ways to iterate over an array or slice in Go. The primary approach is to use range, which handles the iteration for you. However, you can also use a traditional for loop if you need to do something out of the ordinary, like iterating in reverse or skipping every other element.

Iterate over an Array or Slice in Go

There are numerous ways to sort slices in Go.

The simplest way uses some basic built-in functions from Go's **sort** package to allow you to easily sort slices of primitives, that being **Strings**, **Ints** and **Float64s**. Using these sort functions, we don't have control over the sort order as the data will be sorted in ascending alphabetical (for strings) or ascending numerical (for Ints and Float64s) order.

In this lesson, we will take a quick look at the easiest way to sort slices of primitives. We will learn about using some of the handy built-in functions in Go's sort package, including:

* sort.Strings: Sorting a slice of strings
* sort.Ints: Sorting a slice of ints
* sort.Float64s: Sorting a slice of float64s

Sort Primitives (strings, ints, and floats) in Go 

There are numerous ways to sort slices in Go.

In this lesson, we will take a quick look at an easy way to sort a slice of structs or primitives. We will learn about using one of the handy built-in functions in Go's sort package called *sort.Slice*. This function takes a slice to sort as an argument and a *less function* or *less func* for short as the second argument. You will write this *less function* to sort the slice however you wish.

Go's sort.Slice function looks like this: *sort.Slice(someSlice, func(i, j int) bool)*. It's super-easy to write an anonymous *less function* to sort.

As you will see, it's easy to use this *less function* to do simple and even complex sorts of your structs with minimal effort.

Sort Slices of Structs using Go sort.Slice

*Go ^1.12, Node ^12.14.0*

Compiling Go programs to WebAssembly does not require Emscripten, and the process is pretty straight forward. In this lesson, we will learn how to compile a simple Go program to a WebAssembly binary, then execute it with Node.js.

Compile and execute a Go WebAssembly program with Node

*Go ^1.12, TinyGo ^0.12.0, Node ^12.14.0*

The WebAssembly binaries generated by the standard Go compiler are often unnecessarily large. In this lesson, we will learn techniques to optimize Go Wasm binary size with an alternative compiler that is designed for microcontrollers - TinyGo.

Optimize Go WebAssembly binary size with TinyGo

*Go ^1.12*

In this lesson, we will learn how to load and use a Go WebAssembly binary in a web app.

Manually load a Go WebAssembly binary in a browser

*Go ^1.12*

In this lesson, we will see how we can interact with the JavaScript environment by using Go's `syscall/js` module to call and pass values into a JavaScript function, and access variables available in JS land.

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