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Web Development Beginner

TypeScript for JavaScript Developers: The Beginner Path

Add types to the JavaScript you already write, without rewriting your whole project.

Rated 5.0 out of 5 from 2 reviews 20 students

MH Created by Marcus Hale

  • Last updated August 2026
  • English
  • 6h 8m of material
  • 46 lessons

What you will learn

8 concrete outcomes

Every bullet below is something you will have built, shipped or be able to explain by the time you finish the last lesson.

  • Convert an existing JavaScript project to TypeScript incrementally without a rewrite
  • Annotate functions, objects and arrays and let inference handle the rest
  • Model data with unions, literal types, interfaces and type aliases appropriately
  • Understand the tsconfig options that matter and what strict mode really enables
  • Narrow types safely with typeof, in, instanceof and custom type guards
  • Type API responses and third-party libraries, including untyped packages
  • Read and fix TypeScript error messages instead of adding any to silence them
  • Wire TypeScript into Vite, ESLint and your editor for instant feedback

Course curriculum

6 modules · 46 lessons · 6h 8m of material

8 lessons running 1h 04m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

9 lessons running 1h 12m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

9 lessons running 1h 10m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

7 lessons running 56m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

8 lessons running 1h 04m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

5 lessons running 42m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

6 modules · 46 lessons

6h 8m total length

Requirements

Short list, and deliberately so. If you meet these you can start today.

  • Comfortable writing JavaScript, including modules, arrays and objects
  • Node 20 or newer and a code editor with TypeScript support such as VS Code
  • No prior TypeScript or type-system experience needed

About this course

TypeScript is not a new language to learn, it is a checker for the JavaScript you already write. This path treats it that way. You start with a working JavaScript project and convert it file by file, watching the compiler find real bugs that were sitting there quietly, rather than starting from an empty folder and abstract type theory.

The fundamentals come in the order you need them: annotating variables and function signatures, arrays and objects, unions and literal types, interfaces versus type aliases, optional and readonly properties, and enums with an honest explanation of why const objects are usually better. Inference is emphasised throughout, because the goal is fewer annotations that carry more meaning, not types on every line.

You then meet the practical layer: tsconfig options that matter, strict mode explained flag by flag, working with third-party packages and DefinitelyTyped, typing fetch responses safely, narrowing with typeof and in and custom guards, and integrating with Vite, ESLint and the editor. The path ends by converting a small React application, which is where most people first need TypeScript to be genuinely useful.

Topics covered

Frequently asked questions

Still unsure about something? Write to misteryjj100@gmail.com and a human answers, usually the same working day.

No, and the course argues against it. TypeScript allows JavaScript files alongside typed ones, so you migrate the files that hurt most and leave the rest.

Not always. The course shows where any is a pragmatic stopgap, where unknown is the better choice, and how to stop temporary any from becoming permanent.

The TypeScript intermediate course on generics, narrowing and type-level design, which picks up exactly where this one stops.

Checkout is handled on our provider's secure payment page. The moment your payment clears we email your personal access link and access code to the address you used at checkout, and the same link appears in your account library. There is nothing to install and nothing to wait for.

Email misteryjj100@gmail.com within 14 days of your purchase, quote your order number, and we refund the full amount to your original payment method. No form to fill in and no questions about how much of the course you watched.

What students say

Reviews are written by people who bought this course. We publish the critical ones too.

5.0

Rated 5.0 out of 5

Course rating · 2 reviews

Rating distribution

  • 5 stars 100%
  • 4 stars 0%
  • 3 stars 0%
  • 2 stars 0%
  • 1 star 0%
  • CW

    Chen Wei

    Frontend developer

    Jul 2026
    Rated 5.0 out of 5

    Gradual is the right word

    It genuinely does begin with one file inside an existing JavaScript project rather than an empty folder. That matters enormously, because courses that start green-field never tell you what to do about the other two hundred files you already have.
  • MK

    Marissa Kuipers

    Web developer

    Dec 2025
    Rated 5.0 out of 5

    Typing external data was the chapter I needed

    Anybody can annotate a function signature. Nobody explains what to do when an API returns whatever the backend felt like that morning. The narrowing and guard material here is practical and I use it every day.

Your instructor

MH

Marcus Hale

Web engineer and JavaScript educator

  • 259 students taught
  • 12 courses published
  • 4.7 instructor rating
  • JavaScript
  • TypeScript
  • React
  • Node.js

Marcus has shipped front ends for two ad-tech startups and one very large retailer, which taught him more about performance budgets than any blog post could. He teaches JavaScript and TypeScript from the runtime up — event loop first, framework second — then follows the same code through Node on the server side. Every one of his courses ends with a deployed application rather than a folder of exercises. He writes a weekly newsletter on browser performance.

See every course by Marcus Hale
$42 USD

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