 Courses from John Lindquist


While using anonymous functions might seem convenient, they can create difficulties when trying to identify performance bottlenecks during profiling. This lesson will demonstrate how named functions make it easier to pinpoint and address performance issues, ultimately leading to more efficient and debuggable code. Learning this practice will greatly improve your ability to locate and fix performance issues in complex projects.

Always Name Functions in JavaScript


When attempting to load the same module twice in JavaScript you'll hit a cache and code won't re-run. In scenarios where you actually do want to have state in your modules, you'll have to use a cache-busting technique by passing a query parameter to a dynamic import. This lesson walks through how to add a query parameter, how to add the appropriate types for loading dynamic modules in TypeScript, and when these techniques are valuable.

Import the Same JavaScript Module Multiple Times with Cache Busting



The include keyword in GitHub Actions empowers you to add custom variables to your matrix strategy, providing flexibility beyond standard configurations. In this video, we'll explore how include allows you to define specific combinations of variables, enhancing control over your workflow runs. You'll see how this feature enables you to tailor jobs for unique environments or scenarios not covered by the default matrix options. By leveraging include, you can efficiently manage complex build processes with greater precision. This technique helps you streamline your CI/CD pipeline, making it more adaptable to your project's evolving needs.

Use GitHub Actions Matrix Include for Complex Job Configurations


Using Cursor Chat, you can easily reference an entire directory of files and ask it to generate anything based on those files. This opens up the possibility of using your current code as a reference guide to create new code that follows existing patterns. With this approach, the result can be a polished prompt you can use with any AI to generate consistent and reliable output.

Focus less on crafting the perfect prompt upfront - what matters most is testing and iterating based on the AI's responses. The more results you see from the prompt, the more you can reinforce the good results and prune out the bad results until your prompt is polished enough that you can rely on the prompt to give you consistent quality results.


Create AI Prompts Based on a Directory of Files


With Cursor's "Composer" feature, you can select and entire directory and make changes to every file. This video walks through the process of selecting a folder and refactoring all the files from JavaScript to TypeScript. It also demonstrates other tips around generating terminal commands and customizing your main Cursor "Rules for AI".


Run an AI Refactor on Every File in a Directory with Cursor


This lesson breaks down the concept of asynchronous iterators and generators in JavaScript. Using the Node.js glob function as a practical example, you'll learn how Array.fromAsync facilitates the creation of arrays from asynchronous iterables and how generators can improve performance in file processing tasks.

Efficient File Processing in Node.js with Async Generators and Array.fromAsync

Learn the concept of asynchronous iterators and generators in JavaScript and Node.js Array.fromAsync



pnpm ships with a streamlined, easy way of managing Node.js versions for youself and your team. This video demonstrates why pnpm uses a specific version of Node.js, how to configure it globally, and how to set up your project so that anyone who is running your project will automatically use the same version of Node.js even if that version of Node.js is not installed.


use pnpm as a Node.js version manager

**Note:** This course is being actively developed and more lessons will be added in the future.

Cursor is an AI-enhnaced code editor that allows you to call upon the robots to refactor or stub out functions for you with natural language. 

In this course, John will show you workflows that will save you time and effort by utilizing the features such as its mult-line editing and context.

In particular, by giving Cursor's AI the proper context, whether that's lines of code or multiple files, you'll get better output when trying to extend or refactor logic that's present.


Bite-size video tutorials for badass web developers.

egghead

Productive Developer Workflows with AI Enhanced Cursor IDE

How often do you avoid scripting something because it takes too much effort?\n\nScript Kit makes it easy to create and run scripts that solve your daily problems. Create a new script from the prompt then your script opens in the editor of your choice. Write a few lines of JavaScript. Then run the script from the prompt.\n\nSimply put, Script Kit helps you script away the friction of your day.

script-kit

Create, read, update, delete. Four actions that every developer becomes intimately familiar with over their career. Script Kit aims to make this process as pleasant as possible using a `db` helper and what better way to show it off than a Todos app?

You will also learn how to create and switch between tabs through Script Kit's `onTab` and `setTab` methods. 

[Install todos](https://scriptkit.com/api/new?name=todos&url=https://gist.githubusercontent.com/johnlindquist/3bdc967ffbd2f6d72491d07bf720f7e2/raw/a37b0058b502d6ba4bebd7a31a30be8789f5a146/todos.js")

```js
// Name: Todos

import "@johnlindquist/kit"

let { todos, write } = await db({ todos: [] })

onTab("Todos", async () => {
  while (true) {
    let todo = await arg("Toggle todo:", todos)
    let t = _.find(todos, todo)
    t.tag = t.tag === "open" ? "done" : "open"
    await write()
  }
})

onTab("New", async () => {
  let name = await arg("New todo:")
  todos.push({ name, id: uuid(), tag: "open" })
  await write()
  setTab("Todos")
})

onTab("Remove", async () => {
  let todo = await arg("Remove todo:", todos)
  _.remove(todos, todo)
  await write()
  setTab("Todos")
})
```


Build a Multi-Tab Todos App in Script Kit

When you want to collect news sources, airline ticket prices, or any events from sites that don't offer APIs, you can use scrapers to grab elements from off the page. 

Script Kit includes a `scrapeSelector()` helper that takes the URL you want to scrape and the selector you want from the page. Using the `// Schedule` metadata, you can also have this script run in the background on a Chron schedule and collect the data for you.


[Install scrape-tech-news](https://scriptkit.com/api/new?name=scrape-tech-news&url=https://gist.githubusercontent.com/johnlindquist/acd397a2ed487ef2a06c00d2951bed63/raw/3942107d2c92abc2c0317d15b0b3d025c5643ef0/scrape-tech-news.js")

```js
// Name: Scrape Tech News
// Schedule: 0 11 * * *

import "@johnlindquist/kit"

let h3s = await scrapeSelector(
  "https://news.google.com/topics/CAAqJggKIiBDQkFTRWdvSUwyMHZNRGRqTVhZU0FtVnVHZ0pWVXlnQVAB?hl=en-US&gl=US&ceid=US%3Aen",
  "h3"
)

let filePath = home("tech.md")
await ensureFile(filePath)
let contents =
  `

## ${new Date()}

` + h3s.map(h3 => `### ${h3}`).join("\n")
await appendFile(filePath, contents)
```

Scrape a Website on a Schedule with Script Kit

We put a lot of work into browsing the internet every day, it would be a pity to lose it all by closing all of our tabs. 

Script Kit can collect all of the tabs you currently have open in Chrome using its `getTabs` method and store them anywhere you want. 

This particular script converts the tabs to markdown links and stores them in a text file on your file system, but you could convert and store them using any approach you can think of.


[Install save-tabs](https://scriptkit.com/api/new?name=save-tabs&url=https://gist.githubusercontent.com/johnlindquist/4713a161a9ec48932b05436ba6a1a123/raw/33f753586d1a158dfb69d07f29850b6013d59f8b/save-tabs.js")

```js
// Name: Save Tabs

import "@johnlindquist/kit"

let tabs = await getTabs()

let tabsMd = tabs
  .map(tab => `* [${tab.title || tab.url}](${tab.url})`)
  .join("\n")

let notes = await editor(tabsMd)

let filePath = home("tab-notes.md")
await ensureFile(filePath)
await appendFile(filePath, notes)

edit(filePath)
```


Save Chrome Tabs in a Markdown File and Take Notes with Script Kit

Sometimes you just want to select and modify some text you have written somewhere on your system. To help you with this, Script Kit provides a `getSelectedText` and `setSelectedText`. Between these two helpers, your script and use and/or modify the text however you want. 

Applying an npm tool like `title-case` can help when you're not entirely sure when certain words need to be capitalized. In fact, I used the title case script on the title of this lesson!

[Install title-case](https://scriptkit.com/api/new?name=title-case&url=https://gist.githubusercontent.com/johnlindquist/0f8323d6aa599cfd62034351f9d38e8c/raw/625d0afd57ccbf8bf64c62bd135474cecf98c58b/title-case.js")

```js
// Name: Title Case

import "@johnlindquist/kit"

let { titleCase } = await npm("title-case")

let selectedText = await getSelectedText()
let titleText = titleCase(selectedText)

await setSelectedText(titleText)

// This Is the Title of My Next Blog Post
```


Apply Title Case to Text Anywhere Using Script Kit

Developers often keep their dev projects in a specific directory like "dev", "projects", or something similar. Script Kit allows you quickly read all the files of any directory then display them in a list so you can open them in your editor.


[Install open-project](https://scriptkit.com/api/new?name=open-project&url=https://gist.githubusercontent.com/johnlindquist/91cf994e450ecd5d45bce9aef9b345a1/raw/880be2d827b9602afe59d4e230e6753288f5bbb8/open-project.js")

```js
// Name: Open Project

import "@johnlindquist/kit"

let dirs = await readdir(home("dev"))

let selectedDir = await arg(
  "Open Project:",
  dirs.map(dir => ({
    name: dir,
    description: home("dev", dir),
    value: home("dev", dir),
  }))
)

edit(selectedDir)
```

List and Launch Dev Projects with Script Kit

We all have various tasks we need to accomplish with images. Whether it's resizing, optimizing, organizing, uploading, or anything else. Script Kit provides a `drop` component so you can simply drag and drop images into a script and process them in whatever way matches your workflow.


[Open drop-image in Script Kit](https://scriptkit.com/api/new?name=drop-image&url=https://gist.githubusercontent.com/johnlindquist/fe5b06f81cfea0d2dd94f743bc40ed15/raw/40a1b6ab271f7f664d7e54c4b779b056c6195b1c/drop-image.js")

```js
// Name: Drop Image

import "@johnlindquist/kit"

let files = await drop()
let imagePath = files[0].path

let Jimp = await npm("jimp")

let image = await Jimp.read(imagePath)
let newImagePath = path.resolve(
  path.dirname(imagePath),
  `new-${path.basename(imagePath)}`
)
await image
  .resize(parseInt(await arg("Width:"), 10), 100)
  .write(newImagePath)

```


Manipulate Images With Drag and Drop in Script Kit

Chrome allows developers to execute JavaScript using Apple Events. When you enable this feature, you can write scripts that can access and modify the page you're currently browsing. 

You can get the site's contents, update storage, or do any action you would typically do through an extension of the Chrome Dev Tools.

```jsx
let value = await applescript(`
tell application "Google Chrome" to tell window 1
	get execute active tab javascript "

${js}

"
end tell
`)
```

Control Chrome From Script Kit using Apple Events

Many developers use Chrome's Dev Tools as a playground for testing out data and JavaScript features. Script Kit enables you to launch Chrome Dev Tools instantly by simply using the `dev` method. Any data you pass into `dev` will show up in the console so you can inspect and play with the data in any way that you want.

[Install dev-tools-demo](https://scriptkit.com/api/new?name=dev-tools-demo&url=https://gist.githubusercontent.com/johnlindquist/6dcaf61e92819114c7478fefd24a71f8/raw/c2e69bfcff581f7929b881638627201b549d23f1/dev-tools-demo.js")

```js
// Name: Dev Tools Demo

import "@johnlindquist/kit"

let response = await get(
  `https://api.github.com/users/johnlindquist/repos`
)
dev(response.data)
```


Instantly Launch Chrome Dev Tools with Script Kit

This lesson walks through a script that can query a Hacker News API and display the information in Script Kit. 

Learn to do several things using Script Kit's global API methods, such as how to make and inspect data requests using `get` and `inspect`, how to display lists of data using `arg`, and how to display previews of the current selection.

[Install Hacker News Script](https://scriptkit.com/api/new?name=hackernews&url=https://gist.githubusercontent.com/johnlindquist/8728c8f56dd88951127810f0dea818d2/raw/8be4d28aa695f7842b610be258db7cd2e823a239/hackernews.js)

Write a Script with Script Kit to Browse Hacker News

GROQ enables you to join together data in whatever format you want. Based on the dataset, sometimes the query needs to include a subquery where you must track which scope the query is running to be able to compare values against values in the parent scope. The parent scope can be accessed through the `^` so you know which scope the value belongs to.

Advanced GROQ With Parent Scopes and Subqueries

We can also use GROQ's `in` keyword in our filters and negate it using the `!()` syntax. This allows us to exclude items that might be included later on in joins before we even get to the projection stage of our query. This example demonstrates filtering out all of the evolutions of Pokemon since they will be included by joining them into the base Pokemon objects.

Filter Arrays in JSON Based on Other Arrays in GROQ

GROQ enables you to join together arrays of JSON objects by looping through arrays inside of projections and using the `in` keyword to match items based on values. This lesson uses Pokemon to demonstrate matching a base Pokemon with the Pokemon's evolutions from a Pokedex dataset.

Join Together Two Arrays in GROQ

GROQ provides a useful `order` function for sorting the results of any Array in your JSON. Pass in the name of the property that you want to sort on and then the `desc` or `asc` to determine the order and you'll get your data back just how you want it.

Order the Results Returned from a GROQ Query

Mock Service Worker is an API mocking library that allows you to write client-agnostic mocks and reuse them across any frameworks, tools, and environments.



Mocking WebSocket APIs with Mock Service Worker

While running `zod` schema validation agains domain-rich objects, the error message saying that _a string is not a number_ might not be really useful.

Especially, when you need to provide a meaningful feeback to the user, e.g. after they have submitted a form with lots of data.

`zod` allows to customize messages on a very granular level. We can also extract repeatable customization to `zod` error maps.

Finally, in order to process an error message further (e.g. display it to the user), we need to handle the `zod` validation errors effectively. Especially, when a big object validation has failed and we could receive a handful of errors.

That's what we learn in this lesson. 🔥

Customize zod Error Messages and Handle zod Errors Effectively

customize zod validation messages, customize zod schema property messages, reuse error maps across different schemas, navigate through zod error objects

You might want to run `zod` schema checks in different styles.

Sometimes you prefer to conditionally throw the error - that's what `parse` does. But another time you'd prefer to receive a `boolean` property that determines whether the validation was successful or not - and perform further actions accordingly.

Additionally, the error-throwing API of `parse` works extremely well with [TypeScript assertion functions](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#assertion-functions). Their combination is just... perfect! 👌

That's what we learn in this lesson.

Use parse and safeParse Runtime Type-checks with zod

use zod parse function to conditionally throw ZodError, use zod safeParse to get a boolean value and run typescript type guard over success property

In this lesson we learn that TypeScript cannot guarantee correct shapes of responses. That's due to TS performing checks in compile-time, while the response will be availbale in runtime - when TS doesn't exist anymore.

In some situations, such as HTTP requests, runtime type checks such as `zod` are essential for providing quick feedback around data-related errors.

Understand where are the possible mistakes to make while using TypeScript with HTTP calls. Use `fetch` and `axios` along with `zod` schema checks.

Also, note that similar mistakes or mistakes could happen while using web storage (e.g. `localStorage`)

Validate HTTP API Response with zod, fetch and axios

use zod as an HTTP response validation tool along with fetch and axios in order to make sure that the response has expected data structure

In this lesson we learn that the `zod` schemas become the single source of truth.

We shall not update TypeScript types manually, since they are generated automatically from the schema.

Same with validation functions.

Whenever the schema changes, all the rest will update accordingly. It's an important mind shift.

Treat zod Schemas as Single Source of Truth

Zod Schemas are the single source of truth for both typescript types, and interfaces - and runtime validation functions. Schemas should be updated first.

`zod` is powerful, but writing the schemas manually for existing JSON objects, especially big ones, can be time-consuming.

But that's what `quicktype` is for! You can get 80% work done instantly! 🥳

Depending on your need - whether you want to automate the process, or do it just one time, you can:
- use an online app
- use an IDE extension
- run a CLI script
- generate a script to be executed within CI/CD environment/tooling

And this is what we learn in this lesson! 🔥🔥🔥

Get started with zod quickly!

Generate zod Schemas Automatically using Quicktype App, Extensions and Scripts

Use quicktype app, extension or scripts to automatically generate zod schemas from existing json files. Save time and get started with zod quickly!

`zod` is a powerful library allowing to run runtime type-checks.

It's complementary to TypeScript, which does type checks in compile time.

In this lesson we create few schemas that represent primitive type values, along with `zod` utilities which make these more precise. We also create object schemas and nest one inside another.

All schemas are being validated against example values. We analyze how to interpret error messages in case of failures.

Perform Runtime Type-checks on Primitives and Objects with zod

Create zod schemas to validate primitive type and object type values in runtime. Analyze the errors to see how a value doesn't correspond to schema expectations

John Lindquist

Script Kit

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