Learn Babel, Grunt 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

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

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



Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.

node

Tests are really important in the software development cycle. But how we can test if our API - or even a page - will support the web traffic and requests our users will create by accessing them?

In this video, you will learn how to create HTTP load and benchmarking tests in Node.js using the autocannon package. With that, we can make sure our API is not consuming too much memory, CPU, or any other resource that can cause slow responses.

Create Load Tests in Node.js Using Autocannon

Nx has been design to work especially well in large monorepos. One particularity (compare to other monorepo solutions) is that Nx follows the principle of having one single version of a package in the entire workspace. That said, you'll have one version of React, one version of Angular etc.. This helps to keep things consistent, facilitates code sharing as well as easier migrations.
In this lesson we're looking into adding the [material-ui](https://material-ui.com/) package to our React app.

Install and use external npm packages in an Nx Workspace

Leaflet is the leading open-source JavaScript library for mobile-friendly interactive maps. Weighing just about 38 KB of JS, it has all the mapping features most developers ever need.

leaflet

While there are a few options for building maps, [Leaflet](https://leafletjs.com/) is the most popular. Lucky for us, Leaflet is also available as a ReactJS component library with [React Leaflet](https://react-leaflet.js.org/). We'll use both Leaflet and React Leaflet to build a map in our React app.

To get started, we need to install:

[Leaflet (npmjs.com)](https://www.npmjs.com/package/leaflet) and [React Leaflet (npmjs.com)](https://www.npmjs.com/package/react-leaflet)

**[Click here for exercise instructions](https://github.com/colbyfayock/launchtime-workshop/tree/master/lessons/02%20-%20Adding%20Your%20First%20React%20Leaflet%20Map%20to%20a%20New%20React%20Application#1-installing-our-dependencies)**


Install Leaflet and react-leaflet with NPM in a JavaScript Project

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

With Node.js installed, bootstrapping a react app is as simple as executing `create-react-app` with `npx`. No further downloads necessary.

Bootstrap a react app using create-react-app

We take the opengraph image we wrote in codesandbox and copy it into our serverless function. We use Rollup to compile the component into an IIFE (immediately invoked function expression) that can run in our headless browser environment and cover a wide set of rollup plugins that we need for compatibility. We end the lesson having successfully screenshot our opengraph react component from our Netlify Function

**Note**:  Due to Netlify changing their handling, the path in `fs.readFileSync` is affected. Update to:
```js
const script = fs.readFileSync(path.resolve(__dirname, "image.js"), "utf-8");
```

Compiling a React to an IIFE with Rollup to execute and render in a headless browser

The ability to pull in just about anything your project needs from npm is amazing, but it can also lead to bundle bloat if you aren't selective about what libraries you pull into your library. In this lesson, we'll take a look at bundlephobia.com, a tool that provides insights about a library's size. With bundlephobia, you can make informed decisions about what libraries you pull into your project and avoid unnecessary bundle bloat.

https://bundlephobia.com/

Make informed decisions about 3rd party npm libraries with bundlephobia

Git is a free and open source distributed version control system designed to handle everything from small to very large projects with speed and efficiency.

In this lesson we'll start with an empty folder and initialize the project that will serve as the base to build up our own React boilerplate project. We'll also initialize a git repository and walk through checking the repo status, adding files, committing and we’ll take a look at the git log.

Initialize an npm Project and git Repository

Babel has support for the latest version of JavaScript through syntax transformers. These plugins allow you to use new syntax, right now without waiting for browser support.

babel

In this lesson, we'll configure webpack to use the Babel loader for our JavaScript files, allowing us to transpile our source files and generate a bundle for deploying our application.

Configure webpack to Load JavaScript Files through Babel with babel-loader

Converting all of our modern JavaScript into ES5 compatible syntax is a great way to use modern features while targeting older browsers. What happens when the browsers natively support these language features? Then it no longer makes sense to transform that code or to include polyfills that will go unused. In this lesson, we’ll add the `@babel/polyfill` package and configure `babel-preset-env`

Target specific browsers with babel-preset-env and the babel pollyfill

 We map over the initial set of results then use `Promise.all` to efficiently fetch the details of each pokemon rendered in the table. This allows us to add more columns to our pokemon table.

Fetch and display row details with Promise.all in Tanstack Table

map over the initial set of results then use `Promise.all` to efficiently fetch the details of each pokemon rendered in the tanstack table

Create a custom hook to fetch remote data by passing a promise to the React 19 `use` hook. Then render this data in Tanstack Table by memoizing the results and passing them to `useReactTable`.

Render remote data in a Tanstack Table with React 19's use hook and a promise

Create a custom hook using React 19’s use to fetch data with a promise. Render it in a Tanstack Table by memoizing and using useReactTable.

You know when you're deep in the code trenches and need someone to challenge your assumptions? That's exactly what this is about.

Instead of waiting for someone to poke holes in your master plan, you can paste that strategy straight into AI Studio and let it pressure test your ideas. We're talking about using this tool to validate everything from your feature proposals to your ambitious refactoring strategies.

The real magic happens when you hit that microphone button. Now you're in a real-time verbal sparring match. It's like rubber duck debugging but the duck actually pushes back and makes you defend every architectural decision you've made.

Here's the workflow:
1. Drop your master plan into the system instructions
2. Tell the AI to challenge every assumption
3. Hit that mic and defend your choices like you mean it
4. Watch your plan either emerge stronger or get rightfully dismantled

This approach is perfect when you're:
- Stuck in your own head with a complex problem
- Need to validate if your approach holds water
- Want to catch edge cases before they catch you
- Looking for opportunities you might have missed because you're too close to the code

It's like having a senior dev on call 24/7, ready to challenge your ideas and push you to think deeper about your solutions.

Now go forth and get your ideas challenged. Your projects will thank you for it.


An Uncomfortable and Challenging Conversation with AI Studio

In this lesson, you'll learn how to effectively brainstorm your project ideas before working with AI agents. We'll cover:

1. The importance of having a clear plan before starting work with AI agents
2. Using traditional brainstorming techniques to gather your thoughts
3. Leveraging video recording to capture your brainstorming session
4. How to review and analyze websites for inspiration
5. Documenting likes, dislikes, and potential features for your project
6. Using AI tools (like AI Studio) to organize and process your recorded brainstorming session

The lesson emphasizes a modern approach to brainstorming that combines traditional techniques with video recording, making it easier to later process your ideas through AI tools. This method helps ensure that no ideas are lost and that your thoughts can be effectively organized by AI for future reference.

How to Brainstorm Your Project Features to Prepare for AI Agents

Many people share .cursorrules files, but trying to craft your own from scratch is a huge pain. Instead, this lesson shows you how to grab ALL community-created .cursorrules files to build a custom rule set for your projects. We'll use Gitingest and Google AI Studio to gather these examples and generate an awesome starting point customized to your specific project.

Generate Custom .cursorrules for Your Project Based on Community Examples

The GitHub CLI allows you to search issues and filter on different criteria like amount of comments. This allows you to search for real-world situations and pains/solutions people have using different technology. 

With the GitHub CLI in hand we'll drop 100s of issues as context in Googles AI Studio and have Gemini determine the 10 most frequently asked questions. This will give us a sense of how people use a library and where people get hung up.

Search 100s of Issues with GitHub CLI as Context for AI Studio

I often find myself wondering how to use certain APIs in certain situations, and I have a couple of keywords that I try and search up on Google. 

What you can do in this situation is turn to GitHub and see how other people have actually used this code on public projects. The GitHub CLI enables us to run searches like this, and we can take the results and work on them programmatically.

Inside of Cursor with their Composer AI agent, we can search for the files we want, tell the agent to download them, and inspect them for better understanding of how those things work together.

Search All of GitHub's Code and Pass the Results to AI Agents in Cursor

Implement virtual scrolling to handle large datasets in an HTML table. Start with a basic table that renders 10,000 rows of data. The browser can struggle with this amount of DOM nodes to render at one time, especially on low end devices. 

We implement tanstack react virtual to render only the necessary amount of rows the user is viewing. The implementation includes proper column sizing, accessibility considerations, and convenient scroll controls, resulting in a smooth and performant table experience regardless of the dataset size.

Create a row virtualized HTML table with Tanstack Virtual

Learn how to implement virtual scrolling in React tables using TanStack Table and Tanstack Virtual with the useWindowVirtualizer React hook.

The most difficult tasks will require the strongest AI models. And those models simply aren't available as AI agents inside of your tooling. So the best workflows are to drag and drop the files you need to be changed and analyzed inside of a reasoning model such as OpenAI's O1 Pro, then letting it create a giant plan for your dumber AI agents to work on. The key here is that instead of just copying and pasting the entire plan into Cursors Composer or your AI agent, it's to create a file inside of your project and ask your agent to tackle the plan one step at a time. This allows you ample opportunity between each step to test and verify the micro steps along the way. Otherwise, as I've experienced many times, a session can go way off track and you burn a lot of time and burn a lot of AI requests Cursors Composer and it starts churning through a plan Cursors Composer and making lots of unwanted changes. Cursors Composer and it's to guide an AI agent to hold its hand along the way, especially through the most complex tasks. Cursors Composer and the most complex tasks Cursors Composer and the most complex tasks require a step-by-step plan.

Planning AI Agent Sessions with Reasoning Models

AI agents will inevitably make mistakes—it's just a matter of when. A key tool in your toolbox, once they do make mistakes after working on a problem for a while, is to use **git diff** to capture all of the changes they've made. 

Once you have those changes in a text file, you have a portable document that you can test against other AI models. This allows you to move the problem into smarter reasoning models with smaller context windows, helping you isolate and focus on the issue at hand.

**git diff** has been invaluable when working with AI agents because they'll often make many good changes but also slip in one tiny error. Finding that one small mistake is **git diff**’s superpower.

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