View the Frontend Masters video course for TypeScript Fundamentals v3 here

TypeScript Fundamentals v3

Learn everything you need to know in order to confidently and successfully use TypeScript to build a modern JavaScript app.


We'll discuss the goals and agenda of this course, and how to get up and running with the workshop project in 2 minutes or less.

02Hello TypeScript

In this chapter, we'll get hands on with our first TypeScript program and the compiler CLI command, and examine a simple program's compiled output

03Variables and Values

We will begin our study of the TypeScript language with simple variables and functions.

04Objects, Arrays and Tuples

Now that we know how to type simple variables and functions, let's make things a bit more interesting with collections: in JavaScript this includes Objects and Arrays.

05Structural vs. Nominal Types

In this unit, we will explore how TypeScript is fundamentally different from nominal type systems, such as the ones found in Java and C++.

06Union and Intersection Types

We will discuss and explore TypeScript's union and intersection types, which are effectively "AND" and "OR" boolean logic operators for types.

07Interfaces and Type Aliases

TypeScript provides two mechanisms for centrally defining types and giving them useful and meaningful names: interfaces and type aliases. We will study both concepts in depth, and explain when it makes sense to use each.

08JSON types

We will take on our first challenge together: defining types that describe any valid JSON value


So far, we have dealt with function argument and return types. There are a few more in-depth features we need to cover, including multiple function heads and callable types.


TypeScript classes add some powerful and important features on top of traditional JavaScript classes. In this unit, we will take a close look class fields, access modifier keywords and more!

11Top and bottom types

Top types can be anything, bottom types can't be anything. We will also look at three "extreme types" in TypeScript: any, unknown and never.

12Type guards and narrowing

We have explored built-in type guards like typeof and instanceof, but there's a lot more power in type guards, including the ability to define your own!

13Nullish values

There are situations where we have to plan for, and deal with the possibility that values are null or undefined. In this chapter, we will dive deep into null, undefined, definite assignment, and the non-null assertion operator.


Generics allow us to parameterize types, which unlocks great opportunity to reuse types broadly across a TypeScript project.

15Dictionary map, filter and reduce

Many of us use array the higher-order functions map, filter and reduce quite often. Let's build out similar utilities that operate on dictionaries!

16Generics Scopes and Constraints

In this chapter, we'll learn about scopes and constraints, as they pertain to type params, and what the language would look like if we didn't have these important tools

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