Courses for Front-End Web Developers

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


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

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


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


With the introduction of Svelte 5, the Svelte team has created a CLI, `sv`, that unifies all the tasks that previously spread across a handful of CLIS (create, add plugins, and migrate).

This lesson will create a Svelte project using the new `sv` CLI and build a counter component to showcase the new `$state`, `$derived`, and `$effect` runes that ship with the new version.



Get Started with Svelte 5 using the sv CLI

You'll create a SvelteKit project using the sv CLI and build a counter component showcasing Svelte $state, $derived, and $effect runes.



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

How you build with Angular has changed quite a lot over the years.

For example, the `inject` function was introduced in version 14 but you might still be familiar with Angular's constructor injection.

Similarly, structural directives like `ngif` or `ngfor` have been replaced with `@if` and `@for` blocks since version 17 and beyond.

These are patterns that need to be adjusted if you want to stay up-to-date with the latest Angular has to provide.

Luckily, Angular gives you great tools in the form of a migration CLI for supporting your migration efforts as you incrementally update your App from older version features and patterns. 

When you're done with this course you'll know how to target specific features, folders, and files to migrate to the latest Angular version.

You'll learn how to 'migrate':
- Structural directives with control flow syntax
- Constructor dependency inject to inject function
- Make components standalone
- Lazy load routes
- Input/Output decorators to signal-based API


Angular Migrations in Practice

Migrate old Angular patterns for version 18 and beyond

Start with a basic Vite React TypeScript app and enhance it for production use by integrating Nitro as the server. 

This requires a custom Vite plugin for nitro as well as a custom renderer and manually creating Nitro config.

The other way to approach this would be to add Vite to a Nitro app instead. Same basic result.

The [Nitro config reference](https://nitro.unjs.io/config) is a great read of you'd like to explore more options.


Configure a Vite React TypeScript Application on a Basic Nitro Server

Configure a Vite React TypeScript app by integrating Nitro for production, using custom plugins, renderers, and configs.

Quick Get Started style introduction to Vite using `pnpm create vite` with the React TypeScript template.

See [more in the official docs](https://vite.dev/guide/).

Create a Vite App with the React TypeScript Preset

Quick guide to start a Vite app using React TypeScript template with pnpm.

Over the years, your application have grown huge. Sometimes, really HUGE.

Many developers have contributed to the codebase. One day they pushed one coding style, a different one another day. Sometimes even different patterns and solutions for similar problems.

You want to keep your codebase consistent. In the Angular ecosystem, there were well established patterns for doing things the right way ™️. But the old solutions are being challenged by signal-based approach.

Eventually, you ask yourself the key question: **Should you integrate with the NEW solutions or stick to the battle-tested ones, but already considered LEGACY**?

That's a very good question indeed. Don't rush with architectural decisions 🤓.

## First, think of what problems you want to solve by introducing the change.

Do you have 1k LoC Angular components? Maybe even 2k? Do you and your team enjoy working with these? 😏

Where does the **domain logic and state management code** belong to - do you have a clear guidance on which code should be put where? Have you spot that different devs implement similar features in totally different ways?

Do you keep on asking the same questions over and over again: **whether this certain piece of code** should be **imperative** (plain old object properties and variables) or **reactive** (streams)? It'd be nice to keep all thinga reactive, but more often than not, it introduces complexity.

## Second, think of long-term consequences.

You are going to have more than one way to **manage the state**. But is that really an issue? If your codebase is modular, separate modules should not depend on each other in any way. Inner abstractions of one should be invisible to the other, etc.

You are going to introduce a **new tool**. On one hand, you need to learn it, and so does your team. But on the other hand, it's a breathe of fresh air. And it's useful to question the way you've been doing things so far. Maybe there's a more effective way?

You are going to embrace signal-based APIs. And that means taking taking advantage of Zoneless Angular. This means using all modern Angular APIs. And you know that signals are the future. Why would you want to stick to the **less performant, less type-safe, less flexible and, objectively, less effective solutions**?

## Finally, plan your INCREMENTAL integration.

INCREMENTAL is the absolute keyword here. You don't want to tell your PM you need to stop delivering features because of a refactor.

Actually, there's no need for a "refactor". Just pick the first new feature to be implemented. Or pick the one that needs to be extended.

NGRX Signal Store allows you to create both very simple & small stores, as well as bigger ones. **Composition** is the key here.

**Start simple**.

Create a `withState` section with the signals that hold the state. That's already reactive. And relatively simple.

```ts
const initialState: CartState = {
  items: ...,
  rebate: ...,
}

export const CartStore = signalStore(
  withState(initialState)
);
```

Create a `withMethods` section to provide ways to change the state:

```ts
export const CartStore = signalStore(
  ...
  withMethods((store) => ({
    addItem(item: ShoppingItem): void {
      patchState(store, (state) => ({ items: [ ...state.items, item ] }));
    },
    ...
);
```

Create a `withComputed` section to provide all derived computations:

```ts
export const CartStore = signalStore(
  ...
  withComputed(({ items }) => ({
    totalPrice: computed(() => items().reduce(...))
    ...
);
```

**Start simple**.

Now you can (literally) **`inject` this code into your existing solution**. All you need is to inject your brand new NGRX Signal Store implementation into a component, or a service:

```ts
@Injectable()
class ExistingBigService {
  cartStore = inject(CartStore)
  //...  
}
```

and that's it! What's beatiful is that NGRX Signal Store should remain an implementation details (of a component, service, etc). It **shouldn't leak outside to the entire application unintentionally**. Small NGRX Signal Stores help us to **keep logic more modular**.

Don't hesitate - give NGRX Signal Store a try! Start with the [_**Scalable Signals Angular Architecture with NGRX Signal Store**_](https://egghead.io/courses/scalable-signals-angular-architecture-with-ngrx-signal-store-a33abd39) course now!

Integrating NGRX Signal Store with an existing Angular application

Integrate NGRX Signal Store into your Angular app incrementally for modular, reactive state management. Improve consistency and performance with modern APIs.

In React 19, managing script tags efficiently within components can lead to performance enhancements and simpler code structures.

Originally, using script tags directly in a React component involved complex setups, like using `useEffect` to dynamically add JavaScript code. For instance, a component might dynamically inject script tags to load external widgets. This approach, while functional, resulted in multiple script tags and duplicate iframe elements. This duplication not only cluttered the output but also negatively impacted performance by loading scripts multiple times.

The workaround for this would be to manually hoist any common scripts and maybe load them when they weren't needed by any components.

With React 19 we now have a more effective method. This involves directly placing the script tag within the React component's return statement. This approach ensures that React handles the script loading, avoiding the duplication of script tags.

By implementing the script tags this way, the loading initiator becomes React DOM, which efficiently manages script loading and deduplication. This setup prevents multiple requests for the same script when the component is rendered multiple times, enhancing the overall application performance.

Furthermore, directly embedding the script tag simplifies the code, making the component cleaner and more maintainable.

Efficiently Render Script Tags in React 19 Components

Learn how to efficiently render script tags in React 19 components to improve performance by avoiding duplicate script loads and simplifying your code.

Let's learn how to dynamically manage title tags in React 19 applications. Rendering `<title>` dynamically is simple enough, however, a challenge arises when multiple title tags are present in the document, which can lead to issues with screen readers and search engine optimization (SEO). The solution presented involves ensuring that only one title tag is rendered at a time by using conditional rendering.

Also we need to make sure to have a single string within the title tag using a template literal, ensuring our HTML remains valid and optimized.


Deduplicate Title tags with React 19

Learn to manage multiple title tags in React 19 dynamically. Ensure accessibility and SEO by preventing duplicate title tags with clear examples.

In React 19, we can easily add a title tag like "Starship Deets" which then appears in the head section of the HTML even when we render it inside our components. This method also applies to meta tags such as character set and viewport settings, which are also lifted to the head section automatically.

This is an awesome feature because it maintains the same composition style we are familiar with in React components. It simplifies the handling of HTML head elements without needing extra setups like `useEffect` for accessing the head section. Even in situations where our components are rendering within a body element, like within a div, we can manage our head content directly within our components. React takes care of hoisting these elements where they need to go.


Hoist Title and Meta tags in React 19

Hoisting title and meta tags directly in React 19 components allows for simpler composition, similar to other React elements. Manage meta and title tags.

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