 Courses from John Otander

[Theme UI](https://theme-ui.com) is a library created by [Brent Jackson](https://jxnblk.com) for building themeable React apps with [Gatsby](https://gatsbyjs.org). It's built with [Styled System](https://styled-system.com) which provides a constrained set of styling APIs based on props. It uses [Emotion](https://emotion.sh) and [MDX](https://mdxjs.com) underneath which abstracts us away from a lot of the challenges when dealing with global CSS and styling content.

Theme UI uses ["presentational context"](https://johno.com/presentational-context) to allow a component to apply styling to child elements without introducing global styles. You can use a styles object in your configuration to apply theme-aware styles to ensure consistency.

Bite-size video tutorials for badass web developers.

egghead

Theme UI

Gatsby is a blazing fast static site generator built with React. Gatsby gives you all of the modern JavaScript tools you want; set up and ready to go out of the box.

gatsby

Theme UI has a collection of [presets](https://theme-ui.com/presets) you can import into your app and even extend. In this lesson we'll replace an existing theme file with a preset and then extend it.

Use and Modify a Theme UI Preset

[Theme UI](https://theme-ui.com) is a library created by [Brent Jackson](https://jxnblk.com) for building themeable React apps with [Gatsby](https://gatsbyjs.org). It's built with [Styled System](https://styled-system.com) which provides a constrained set of styling APIs based on props. It uses [Emotion](https://emotion.sh) underneath which abstracts us away from a lot of the challenges when dealing with global CSS.

Theme UI uses ["presentational context"](https://johno.com/presentational-context) to allow a component to apply styling to child elements without introducing global styles. You can use a `styles` object in your configuration to apply theme-aware styles to ensure consistency.

Introduction to Theme UI

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

If you want to offer more than two color modes in your Theme UI-based site you can create a button that can activate all color modes. In this lesson we'll add two new color modes, for a total of four, and then use the `useThemeUI` hook to create an array of color modes to cycle through.

Cycle Through Multiple Theme UI Color Modes

Theme UI has built-in [color mode support](https://theme-ui.com/color-modes/) that makes it straightforward to add a dark mode to your Gatsby project. You can use the `useColorMode` hook to retrieve the active color palette and set it to a predefined dark color palette.

Add Dark Mode to a Gatsby Site with Theme UI

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

You can use unified's [virtual file](https://github.com/vfile) to add data from a document in order to use it elsewhere. In this lesson we'll store metadata from all heading nodes in a markdown document using remark and vfile.

Store Heading Metadata in a Markdown Document with remark

[Theme UI](https://theme-ui.com) provides a wrapper around the MDXProvider so you can add styling to components that are rendered in your MDX documents. The styling you add will not be leaked as global styles since it relies on React Context and Emotion. The values set in the `styles` object are [theme-aware](https://theme-ui.com/theming) so you can ensure consistency when applying color and typographic styles to your content.

This lesson uses `gatsby-plugin-theme-ui` in order to seamlessly integrate Theme UI into a Gatsby site.

Style Components Rendered By MDX with Theme UI in Gatsby

[unified](https://unifiedjs.com) enables new exciting projects like [Gatsby](https://gatsbyjs.org) to pull in Markdown, [MDX](https://mdxjs.com) to embed JSX, and [Prettier](https://prettier.io) to format it. It’s used in about 300k projects on GitHub and has about 10m downloads each month on npm.

unified uses abstract syntax trees, or ASTs, that plugins can operate on. It can even process between different formats. This means you can parse a markdown document, transform it to HTML, and then transpile back to markdown.

unified leverages a syntax tree specification (called unist or UST) so that utilities can be shared amongst different formats. In practice, you can use unist-util-visit to visit nodes using the same library with the same API on any supported AST.

unified - the compiler for your content

Cascading Style Sheets bring order and beauty to our applications.

You can use the background-clip CSS property to create text gradients that are made up of selectable text. This approach can be used with background images as well.

```css
h1 {
  font-size: 100px;
  background-image: linear-gradient(300deg, tomato 25%, red 80%);
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}
```

Create a Text Gradient in CSS with Background Clip

[regexr](https://regexr.com) is a powerful tool for debugging existing regexes and creating new ones. In this lesson, we'll use the app to create a regex that matches Twitter-style mentions in a string. It will go over a few regex concepts including capture groups, character sets, and flags.

Construct a Regex to Match Twitter Mentions with Regexr

When you use a component for your table of contents in MDX documents you have more flexibility around how you render it. In this lesson, we'll use Gatsby's GraphQL data layer to fetch the headings in an MDX document and pass them to a TableOfContents component that we create.

Create a Table of Contents Component for MDX Documents in Gatsby

You can use the remark CLI to inspect the AST, run plugins, or lint your markdown documents. It can be used in your build scripts to generate HTML or ensure your markdown style guide is adhered to.

- Inspect the AST: `remark document.md --inspect`
- Use a plugin: `remark document.md --use toc`
- Overwrite your document after the plugin runs: `remark document.md --use toc -o`
- Lint a document: `remark document.md --frail --use preset-lint-markdown-style-guide`

Introduction to the remark CLI

[PostCSS](https://github.com/postcss/postcss) is a CSS processor that allows you to modify source CSS with plugins. In this lesson we'll modify the CSS AST by creating a plugin that removes declarations when they contain vendor prefixes.

Create a PostCSS Plugin to Remove Vendor Prefixes

Most of the time with markdown documents we want to render them to HTML for static websites. You can use remark and the [remark-html](https://github.com/remarkjs/remark-html) plugin to transpile your markdown documents to HTML with a build script.

Convert Markdown to HTML with remark-html

Manually maintaining a table of contents in markdown documents can be a lot of work. By combining [remark-toc](https://github.com/remarkjs/remark-toc) and [remark-slug](https://github.com/remarkjs/remark-toc) you can ensure generate your table of contents and ensure it's always up to date.

Add a Dynamic Table of Contents to Your Markdown Documents with remark-toc

When using remark to manipulate markdown documents, you can use [unist-util-remove](https://www.npmjs.com/package/unist-util-remove) to remove nodes of a particular type. You can combine it with [unist-util-visit](https://www.npmjs.com/package/unist-util-remove) to remove nodes based on their parent's context in the AST.

In this example, we remove all images contained within heading nodes.

Remove Markdown Nodes from a Document with unist-util-remove

[remark](https://github.com/remarkjs/remark) is a pluggable markdown parser and compiler. It's part of the [unified](https://unifiedjs.com) so it offers a wide array of libraries to make writing plugins with the markdown AST ([MDAST](https://github.com/syntax-tree/mdast)) more developer friendly.

We'll use `unist-util-visit` to traverse heading nodes in a Markdown file and prefix all `h1`s with the text "BREAKING" using a TDD workflow.

Create a remark Plugin to Modify Markdown Headings

When comparing two visually similar websites, it can often be challenging to precisely identify the subtle differences between them. To facilitate a rapid analysis of these discrepancies, a practical technique involves leveraging Chrome's integrated developer tools to capture full-page screenshots of each site. Subsequently, these screenshots can be uploaded to a platform like AI Studio. There, the AI can analyze the images and generate a report detailing the variations. This entire process, leveraging a few quick shortcuts, can be completed in under a minute, delivering a comprehensive breakdown of the differences for efficient comparison and analysis.

Quickly Compare Two Sites Using AI Studio with Chrome Full Page Screenshots

It's fairly trivial to create a React project, but there's always a big hurdle between creating it locally and making it shareable so that someone else can run it. This lesson walks you through the process of automating creating a React project locally, creating the repository where it's going to be hosted, and creating shareable links where it can be run so that you can quickly and easily create single one-off demos and shoot them over to your friends and coworkers for sharing your code ideas in a working environment.


```bash
share-react-project() {
  if [[ -z "$1" ]]; then
    echo "Usage: share-react-project <project_name>"
    return 1
  fi

  local project_name="$1"
  local github_username=$(gh api /user --jq '.login')

  echo "Creating Vite project: $project_name"
  pnpm create vite "$project_name" --template react

  cd "$project_name"

  echo "Initializing Git repository"
  git init

  echo "Adding all files to Git"
  git add .

  echo "Creating initial commit"
  git commit -m "Initial commit"

  local codesandbox_link="https://codesandbox.io/p/github/${github_username}/${project_name}"

  echo "Adding CodeSandbox link to README.md"
  echo "" >> README.md
  echo "## CodeSandbox" >> README.md
  echo "[![Open in CodeSandbox](https://assets.codesandbox.io/github/button-edit-blue.svg)](${codesandbox_link})" >> README.md

  echo "Adding README.md to Git"
  git add README.md

  echo "Committing README.md changes"
  git commit -m "Add CodeSandbox link"

  echo "Creating GitHub repository: $github_username/$project_name"
  gh repo create "$github_username/$project_name" --public

  echo "Pushing to remote 'origin'"
  git push -u origin main

  echo "Project '$project_name' created successfully!"
  echo "GitHub repository: https://github.com/$github_username/$project_name"
  echo "CodeSandbox link: $codesandbox_link"
}
```

Automate Creating a Local React Project, GitHub Repository, and Live Hosted Demo in a Single Command

[Verdaccio](https://verdaccio.org/) is a fully featured NPM registry that you can run locally on your machine. It’s a great tool for testing your release process, running end-to-end tests, and simulating real-world scenarios like deploying packages, installing them, and verifying functionality as an end user would.

Nx includes a [generator](https://nx.dev/features/generate-code) that simplifies setting up Verdaccio. To configure it, run:

```shell
npx nx g @nx/js:setup-verdaccio   
```

This command installs the necessary NPM packages and creates a `project.json` file with a `local-registry` target. To start the local registry, open a new terminal window and run:

```shell
npx nx local-registry
```

This will:
- Launch the Verdaccio registry.
- Configure NPM to point to the local Verdaccio server at `http://localhost:4873`.

> **Note:** A `project.json` file provides an advanced way to define scripts, offering more flexibility than a traditional `package.json` for managing complex targets.

Setup local Verdaccio server to release NPM packages

Learn how to spin up a local NPM registry powered by Verdaccio to test deploy your NPM packages.

In TypeScript, developers often begin by defining the structure of their data using type definitions or interfaces, which is a powerful way to ensure type safety. However, as applications grow and become more complex, simply defining the shape of an object might not be enough to guarantee its consistent creation and behavior throughout the codebase. This often leads to situations where objects that are intended to be of a certain "type" might be missing crucial properties or have incorrect data, which can be difficult to track down and debug.

This lesson tackles the question of when and why to move beyond basic type definitions and embrace classes in TypeScript. It demonstrates how classes provide a more robust mechanism for defining object structure, enforcing type constraints, and ensuring consistent object creation. By establishing a clear blueprint for objects, classes not only improve compile-time type safety but also offer runtime benefits and better code organization, ultimately helping developers avoid common pitfalls associated with loosely structured objects in larger TypeScript projects.

Stop Avoiding Classes in TypeScript

Karabiner isn't only for your keyboard. It can also hijack your mouse buttons and enable them to be similar to layers on your keyboard, where holding down a mouse button can allow you to tap keys on your keyboard to trigger commands and macros that can completely revolutionize your workflows. For example, you can hold down the right mouse button and tap on R to go to references in VS Code. Or hold down the right mouse button and tap the left mouse button to chop up videos and Screenflow.

This completely unlocks a whole new world of possibilities and use cases for your mouse as you can hover your mouse over anywhere on the page. And just tapping keys on your keyboard allows you to trigger mouse actions, to trigger keyboard actions, or to trigger macros and applications and terminal commands. and anything that your imagination can come up with. 

Karabiner: Rethinking Right-Click as a Macro Command Center

Make an HTML table more readable on mobile devices by using the ::before pseudo-element. We add labels to each cell, so they appear like cards when the table is viewed on smaller screens. The ::before content is set using a data-label attribute for each cell to enhance mobile viewability without horizontal scrolling.



Create a mobile friendly table with the before pseudo-element

Learn to use CSS ::before pseudo-element for mobile-friendly HTML tables. Add labels to cells for enhanced readability on mobile, avoiding horizontal scroll.

Any app of a decent size has event flows and messages being passed around. At a certain point it becomes complicated to explain it through prose and you want to turn towards diagrams. Now setting aside the time to create diagrams that accurately describe what's happening in your codebase can be quite time consuming. Luckily, with today's AI tools, we can now just do basic walkthroughs with rough recordings over codebase dictating what's going on along the way and then upload that to tools like AI Studio and then ask it to generate diagrams in a text-based format such as Mermaid that will then generate the flowcharts and diagrams for us. So this video walks us through this process of recording a rough video, uploading it to AI Studio and then asking AI Studio to generate the proper Mermaid diagram syntax.

Generate Mermaid Flow Chart Diagrams with Gemini 2.0 from Rough Screen Recordings

I'm a diehard Karabiner user and anytime I start doing something repetitively I always move it into my Karabiner configuration. Sometimes I'll fall into scenarios where I want to trigger a command, but I also want to know if that command succeeded or failed. Since Karabiner can trigger any command, setting up the command is fairly straightforward, but knowing whether it succeeded or failed became much more difficult. Luckily for me there is a package called terminal-notifier that you can install from homebrew and you can pipe the output of your command to terminal-notifier. And have a seamless way of triggering your keyboard shortcut which runs a command and you can be notified of the results.

Use Karabiner to Trigger a Terminal Command and Get Notified of the Results

There are a lot of scenarios when inspecting a site in Chrome where you don't want any click events to fire and you don't want any scripts to run. Or maybe something is animating in and out of the page and you want to capture it at a certain moment. This is a great use case for pausing script execution, which is kind of using the debugger manually by going into the Chrome DevTools and the Sources tab and clicking the pause button to essentially pause the entire page. This will give you a chance to inspect any of the elements and styles you want to inspect. And you don't have to worry about fire and click events or anything that might interrupt your investigation into the elements and styles that you want to find.

Pause Script Execution in Chrome to Easily Inspect Elements

Gemini 2.0 has a context window of a million tokens, and this means that you can upload hundreds of files and allow it to inspect and analyze massive refactors across entire code bases. 

This lesson demonstrates concatenating an entire code base into a single file and then uploading it to AI Studio. Once within AI Studio, we ask it to find the types of tasks that it can evaluate for us. Then we select one of the tasks and ask it to generate instructions for that task. Once those instructions are complete, we then turn them over to Windsurf's Cascade agent, and we allow Windsurf's Cascade to do all of the work for us as we sit back, relax, and let the AI do our jobs.

John Otander

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