Learn Chrome, Express and Npm

A Monorepo is where you have multiple projects inside a singular repository.

monorepo

Introduction to Monorepos with NPM Workspaces

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.

Thank you for completing my course!

You’ve learned what monorepos are, how to create them from scratch, how to install different projects inside of it, and how to run different scripts inside of a monorepo. 

So where do you go from here? I suggest creating your own Monorepo project template and publish it on Github. Take a look at Yarn Workspaces, pnpm, Learna, Nx and Turborepo for different monorepo tools. 

I also highly suggest Migrating some of your existing projects to a monorepo. Have a main frontend application that consumes a shared UI library package and a backend service. Another way would be to have a backend service, a mobile application and a frontend application. 

Best of luck and happy coding!

Intro to Monorepos with NPM Workspaces Outro

All of our applications and libraries have `test` and `typecheck` commands already written inside of them. We are able to run both the `test` and `typecheck` commands all at the same time as well. 

This has a downside. They don’t run at the same time, it’s just one after the other. To make them run at the same time, we will implement `concurrently` again.

Running Quality Checks in your Monorepo

We already have a utils package that outputs JavaScript. If we want to use that package inside any of our applications, in our case, blog or dashboard, we would have to install it first.

Share Code Between a Library and Applications Inside a Monorepo

Right now, it is not possible to run all the Dev Scripts across all the packages of the monorepo at the same time, because once we run `npm run dev` with the `-ws` flag, we will run the dev-command in the block first, but that command never ends. It is always watching for changes.

In order to run the `dev` scripts across all the packages in the monorepo, the first thing that we have to do, is to create a dev command for each one of the packages in the root package.json file. Then we can use `concurrently` to change them. We go `concurrently` and we tell it to run the utils, then the blog and then the dashboard scripts.

Run Dev Scripts for All Packages Simultaniously

We can install a dependency inside a monorepo by running npm install, then the name of the dependency, in our case, it’s going to be Lodash. But, we are going to add different flags to that.

If we use the `-w` flag, we would have to specify in what package we want to install Lodash. We will do this for `monorepo/utils`. We could also use the `-ws` flag to install Lodash across all the packages in the monorepo. We can also use `-W` in uppercase to install Lodash in the root of the project.

Install Dependencies for Specific Packages in a Monorepo

To run specific commands inside a monorepo we have to type `npm run` then the name of the command, `build`. We then add the flag `-w` for watch mode and specify which package we want to run the build command. In this case, it’s going to be the `utils` package. 

The full command will look like, `npm run build -2 @monorepo/utils`.

If you want to run all of the commands, you'll need to add the `-ws` flag. 

The full command for running all of our build commands will look like, `npm run build -ws`. 

Run App Specific Commands in a Monorepo

Creating a TypeScript library inside the monorepo is easy if we use tsup. To configure tsup, we have to set up the entry point. In our case, it's going to be the index.ts file inside the src directory.

We will also specify some extra options for tsup such as generating the types and source maps. We can also output different formats. In this case, we want to output an ESM file and a CommonJS file.

Add a TypeScript library to your Monorepo using TSUP

In order to create applications inside our monorepo, we can use different CLI tools like create-next-app or the Vite CLI. We'll install them inside the apps folder. We will create a blog and a dashboard app, one using create-next-app and the other using the Vite CLI.

It is also important to note that the only package-lock.json file that should exist, exists at the root of the project.

Install a Next.js and a Vite.js Applications Into a Monorepo

For this course, we are going to be using NPM Workspaces to configure our monorepo. We will have two workspaces, one for our apps and one for our libraries. We configure those in our package.json.

Configure NPM Workspaces in your Package.json

A monorepo is a group of small projects that can be combined to build bigger projects, or they could just be small projects that doesn't know anything about the other projects.

One great thing about monorepos is that the code is available for everyone at every time. If you are a frontend engineer, and you're working in the blog application and you see that there is a bug in the backend application, you can go and fix it right away.

What are Monorepos

“a11y” stands for “accessibility.” It is a numeronym, with 11 representing the count of letters between the letter a and the letter y.

Accessibility is broken down into 4 categories of disability: visual, cognitive, auditory, motor. 

Regardless of the category of disability, accessibilities aim in web development is to make applications and websites usable for everyone.

a11y

To audit our app for accessibility issues at runtime we can use Cypress to run our application in a browser environment and then with the aid of the axe-core `cypress-axe` library we can analyze the current page for any accessibility issues.

## Resources
* https://www.cypress.io/
* https://github.com/component-driven/cypress-axe
* https://mochajs.org/#bdd
* https://www.chaijs.com/guide/styles/

Write E2E Tests for Accessibility Using aXe-core and Cypress

JavaScript® (often shortened to JS) is a lightweight, interpreted, object-oriented language with first-class functions, most known as the scripting language for Web pages, but used in many non-browser environments as well such as node.js or Apache CouchDB. It is a prototype-based, multi-paradigm scripting language that is dynamic, and supports object-oriented, imperative, and functional programming styles.

javascript

To audit our app for accessibility issues at runtime we can use Selenium WebDriver to run our application in a browser environment and then with the aid of the aXe-core `webdriverjs` library we can analyze the current page for any accessibility issues.

## Resources
* https://www.selenium.dev/documentation/getting_started/installing_browser_drivers/
* https://github.com/dequelabs/axe-core-npm/blob/develop/packages/webdriverjs/README.md 

Test Accessibility at Runtime with Selenium WebDriver and aXe-Core

Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.

express

Learn about security headers by adding them to an Express app in a step-by-step guide.

We're going to cover:
- default request headers
- what are security headers
- why security headers are important
- how to add security headers using Helmet
- how to configure the newly added security headers

Add Security Headers to an Express app

There are some really known patterns to migrate packages in large applications. You might find some code referencing to a different package (such as `@my-namespace/my-package/next`) or specific branches (like `@my-namespace/my-package#next`). 

Anything that helps during package migrations or bumps having several majors of differences.

The good news is that you can have it done directly via NPM! What can be done in this case is an idea called "package alias". So you can have multiple versions of the same package running in your app and you can work on the upgrades mitigating possible issues.

Install Multiple Versions of the Same Package in NPM with Package Aliases



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

In this lesson we install the [Redux Dev Tools](https://github.com/zalmoxisus/redux-devtools-extension#installation) extension into Chrome and demonstrate how it lets you inspect the various actions passing through your redux store as well as all of the data it contains. We also briefly demonstrate the time travel debugging capability as we walk back through and un-add items to our shopping cart.

The key here is that because we used [configureStore](https://redux-toolkit.js.org/api/configureStore) from RTK which automatically includes support for redux dev tool without having to explicitly turn it on.

Using the Redux DevTool Support Built-in to Redux Toolkit

We'll create our client-server using the `express` and `cors` packages

Express will be used to create our HTTP application. We'll need it to post to our endpoints and listen to our port.

We need the `cors` package to make cross-origin requests since the front-end will be a different origin than the server.

Create an OAuth Client-Server for code/token exchange

 Every developer who has attempted to demystify OAuth 2.0 must be presented with mind-bugging complicated flow diagrams. It becomes worse when you try to understand all the terminologies of OAuth 2.0 and Open ID protocols.

There is no getting around the OAuth 2.0 flow being complicated with back and forth between your browser, the service you are authenticating with, and the application you want to access. 

This course gets straight to the point without any application code distracting you from the core takeaway -- You will learn how to authenticate and authorize yourself using GitHub as your Auth Server.

We'll first cover the OAuth 2.0 flow for authentication and then integrate the Open ID protocol for authorization.

[**LIVE EVENT**: Register here for a live webinar with Christian on OAuth.](https://egghead.zoom.us/webinar/register/WN_Sxy1FEcoTea8UA6F7EDzLw) Bring any questions you have from taking this course!

JSON Web Tokens are an open, industry standard RFC 7519 method for representing claims securely between two parties.

Add Github Login to Your Web App with OAuth 2.0

Cascading Style Sheets bring order and beauty to our applications.

In this lesson, we take a look at how to animate and transition custom properties with CSS Houdini @property. It hasn't been possible to animate and transition background-images and other properties until now. This demo will show you how to define custom properties and define type checking for them.

Check for [Browser Compatibility](https://caniuse.com/mdn-css_at-rules_property).

Use CSS @property to Animate and Transition Custom Properties

In this lesson, we take a look at the CSS aspect-ratio property and see how we can define different aspect ratios for elements.

Check for [browser compatibility](https://caniuse.com/mdn-css_properties_aspect-ratio).

Use CSS aspect-ratio to prescribe an aspect ratio for an element

CSS Media queries are heavily used across web pages for different reasons, such as make your web pages responsive, but what if we can use them to improve web accessibility as well?

In this video, I’m sharing How to use CSS Media Queries for web accessibility in your web app, combining the user preferences choice with `prefers-color-scheme` media query and enabling dark mode in your web app.

Create a Dark Mode Theme in Your Web App Using CSS Media Query

Get started with MongoDB and Docker really quick 🔥 even if you have no backend/fullstack experience.

This lesson guides you through installing Docker Desktop and setting up a MongoDB image.

We explain Docker images and containers, and their roles in providing isolated software environments.

We run a MongoDB image in 2 ways: using the terminal and Docker Desktop

We demonstrates configuring port settings for a container and accessing the MongoDB shell (`mongosh`) to interact with the database.

We learn how to manage Docker containers, configure settings, and run commands inside the container.

Grab the CLI command: 🔥 `docker run --name some-mongo -d mongo:latest` 🔥

Tomasz Ducin

Install Docker to run local MongoDB Container

Learn to install Docker Desktop, set up a MongoDB image, and manage containers. Configure ports and access the Mongo shell

Learn how to test custom ESLint rules with Vitest and RuleTester.

In the [previous video](https://egghead.io/set-up-a-custom-es-lint-rule~kq49h), we created a custom eslint rule that gives us a warning when some of the class names don’t start with a lowercase letter.

Here, I'll show you how to test this or any other custom ESLint rule using unit tests without manually restarting the ESLint server or modifying production code to check if the rules work correctly. We'll look at the structure in which correct and incorrect code samples should be specific to RuleTester.

We'll also learn how to make our rule fixable and verify that the applied fix works as expected.

Ákos Kőműves

Test Custom ESLint Rules with Vitest and RuleTester

Learn to test a Custom ESLint Rule using Vitest and RuleTester.

This course is designed to make you proficient in building dynamic data tables in React using TanStack Table. 

You'll learn to fetch and display remote data, handle pagination, and implement row virtualization for better performance. 

The lessons guide you through customizing table cells with your own JSX components, adding features like toggling column visibility to enhance user interaction, and create mobile-friendly tables with CSS pseudo-elements. 

By the end, you'll have the skills to create efficient, user-friendly tables that elevate your React applications.

Ian Jones

Headless, Mobile-friendly Data Tables with Tanstack Table and React

Learn to display, paginate, and virtualize data effectively in a table with Tanstack table and React 19.

Install `ghx` with `npm i -g @johnlindquist/ghx`

https://github.com/johnlindquist/ghx

You've copied and pasted code, set up your project, and... *error*.  "Stream is not readable."  Sound familiar?  Generic Google searches and outdated Stack Overflow answers often leave you more confused than when you started.  You need more than just documentation; you need *context*.  You need to see how real developers solve this *exact* problem.

This lesson shows you a better way to debug, using real-world GitHub examples and the power of Cursor's Composer.

Here's the workflow we'll cover:

1.  **Identify the Error:** You've already done this!  You have a specific error message ("Stream is not readable") and the code that's causing it.
2.  **Find Real-World Solutions with `ghx`:** We'll use `ghx`, a tool for searching GitHub, to find *actual projects* that have encountered (and solved!) this same issue.  No more generic advice – you'll see working code.
3.  **Consolidate and Analyze:**  `ghx` brings those relevant code snippets into a single, easy-to-read file.
4.  **Leverage Cursor's Composer:** We'll use Cursor's Composer to directly interact with the examples and your problematic code.  Paste in your error, reference the `ghx`-generated file, and ask targeted questions like:
    *   "Based on these examples, how should I modify my code to fix the 'stream is not readable' error?"
    *   "What's the common cause of this error in the context of an MCP server?"
    *   "Show me the specific lines in the examples that handle stream readability correctly."
5. **Fix the Error:** Implement the solution using this workflow.

Instead of guessing, you'll learn directly from proven solutions.  You'll gain a deeper understanding of your issue and how to troubleshoot it effectively.  This approach transforms debugging from a frustrating hunt into a targeted learning experience.

John Lindquist

Fix Real-World Coding Errors with GitHub Context through ghx and Cursor Composer

AI is amazing for generating code, but often leaves us staring at functions and libraries we've never seen before. This creates a huge problem: When things break (and they will break), we're lost. We don't understand the individual pieces, let alone how they interact. Knowing one part isn't enough; we need to see how unfamiliar components work together.

The solution? Real-world examples.

This lesson introduces ghx, a tool I built to do exactly that. ghx searches GitHub, finding actual code examples that use the specific combinations of functions and libraries that are tripping you up. Instead of generic documentation, you get concrete implementations. You can find the ghx repository at https://github.com/johnlindquist/ghx.

Here's the workflow we cover:

Identify the Unknown: Pinpoint the AI-generated code you don't understand – specific functions, libraries, or their interactions.

Search with ghx: Use ghx to search GitHub for examples using those terms together. ghx finds repos where those elements co-exist.

Consolidate Examples: ghx combines the relevant code snippets from those examples into a single, digestible file.

Ask the AI (Again, but Better!): Feed this consolidated code to an AI (like a coding-focused model in an AI studio). Now, instead of asking general questions, you can ask targeted questions based on real-world usage:

"Explain how these functions are used together in these examples."

"What are some common use cases for this combination of libraries?"

"Show me alternative code snippets that achieve the same result."

"Can you identify potential problems or areas for improvement, based on these examples?"

Iterate. Use your improved understanding to make changes, and then repeat the process to debug.

By leveraging ghx and targeted AI prompting, we transform from being lost in a sea of unfamiliar code to actively learning from how others have solved similar problems. We gain a deeper understanding of our AI-generated codebase, making debugging, modification, and future development far more manageable. This gives you the tools to understand, debug and improve your own code.

How to Work with AI-Generated Code You Don't Understand with ghx and Gemini

In this less we create a custom Zod schema using `z.custom`.

The example case covers room numbers validation: it must start with an uppercase letter followed by three digits. `z.custom` allows the creation of a brand new custom schema with a callback function that returns a boolean indicating validity.

We highlight a challenge with type inference in Zod's custom schemas: callback parameter types don't get aligned automatically - type-safety must be explicitly defined using type parameters.

We run tests against various room numbers and demonstrate how to effectively validate inputs and manage error messages.


Create Custom Zod Schemas and Validate project-specific data

Create custom validation logic in Zod using z.custom, for primitive values, ensuring type safety and proper error messages for room numbers.


Excessive properties refer to any additional attributes that are not explicitly listed in an object schema. When creating an object based on a schema, it is important to ensure that only the defined properties are included.

In TypeScript, if an object is created with an extra property that isn't defined in the schema, TypeScript will not raise an error unless the type is explicitly annotated. When the type is annotated, TypeScript will issue an error indicating that the extra property is not allowed.

Zod provides a strict utility to enforce similar checks. This feature ensures that only specified properties are allowed in an object schema. When unnecessary properties are added at both the top level and within nested schemas, Zod will throw errors indicating unrecognized keys.

Adding an unrecognized property to a Zod schema results in an error message that specifies which keys are not recognized. Applying strict checks on nested schemas ensures that all levels of the data structure are validated correctly.


Make Excessive Object Properties Fail on Zod Validation

Prevent excessive properties in TypeScript and Zod schemas using strict checks for better data validation

In this lesson we discuss how Zod works with TypeScript to handle special types like `undefined`, `null`, `any`, `unknown`, `never` and `void`.

We modify our room booking schema to demonstrate the use of `optional` and `nullable` Zod utilities.

By using `.optional`, we allow a property to be either its _original type_ or `undefined`. With `.nullable`, we allow it to be either its _original type_ or `null`. Finally, `.nullish` allows a value to be either its _original type_, `null`, or `undefined`.

For all cases, we run tests to show how these schemas work in practice, as well as how TypeScript infers types.


Declare Lack of Value in zod (optional, nullable and nullish)

use Zod for TypeScript schemas, including handling undefined, null, and special types like optional and nullable values, as well as any, unknown never and void

In this lesson we make use of partial validation of large and nested schemas in Zod.

Instead of creating many small schemas, which can complicate maintenance, Zod allows for the extraction of specific parts of a schema using the concept of ".shape". It "unwraps" the object schema, enabling access to sub-schemas within specific properties.

Additionally, we can use the `.unwrap` to get into element schemas of altered schemas such as `.optional` or `.array`.

Simplify working with complex schemas without the need to break them into hundreds of small schemas.

Use Zod Schemas partially using shape and unwrap

Manage large and nested Zod Schemas by extracting partial validations using shape and unwrap utilities

In this lesson we cover implementing sets and maps in Zod.

Using `z.set`, a schema for string-based amenities is created. We demonstrate how validation works by intentionally introducing errors and customizing error messages for better clarity.

Next, a map is created for existing guestDetails schema using `z.map`, with string keys and an existing `z.object`-based schema. The validation process is shown again by deliberately breaking the schema, such as omitting the age property, which triggers appropriate error messages.


Validate maps and sets using Zod schemas

Use sets and maps in Zod for schema validation, ensuring type safety for both keys and values.

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