TypeScript 7.0 Programming in 14 Days

Fourteen days. One project. Every listing executed.

This is a drill manual, not a tutorial. Every rule of the TypeScript type system is stated in as few words as it can be, shown working in a short program with its real captured output, and then handed straight back as problems. Every listing was run on TypeScript 7.0.2 and Node v24.13.1, and every printed block, diagnostics included, is a paste from that run. Nothing here is written from expectation.

TypeScript 7.0 replaced the compiler with a native Go implementation. Two changes meet you on Day 1: strict is on in a new project by default, and the es5 target has been removed. Both are shown happening on the page.

What you will build

One project runs through the whole book: shiftlog, a shift-scheduling service on Node. It starts as a single typed function on Day 1 and ends on Day 14 as a package with declarations, source maps, a referenced build, and a pipeline that gates one step on another. No day uses anything an earlier day has not introduced.

The fourteen days

Week one - the type system.

• Day 1 - The Compiler, the Project and the First Type


• Day 2 - Primitives, Literals and Inference


• Day 3 - Objects, Interfaces and Structural Typing


• Day 4 - Unions, Narrowing and Discriminated Unions


• Day 5 - Functions, Parameters and Overloads


• Day 6 - Arrays, Tuples and Readonly


• Day 7 - Generics

Week two - the type system at work.

• Day 8 - Conditional and Mapped Types


• Day 9 - Classes, Accessibility and Abstraction


• Day 10 - Modules, Resolution and Declaration Files


• Day 11 - Asynchronous Types


• Day 12 - Validation at the Boundary


• Day 13 - Strictness and Migration


• Day 14 - The Build

Inside

• 398 worked examples, each a complete program with its real output and a figure


• 398 figures, drawn to read in black and white


• 802 numbered problems in five sets a chapter: review questions, worked problems, worked programming problems, practice problems, practice programming problems


• 468 listings executed, every one on the versions above


• Every diagnostic printed with its code, because the code is what you search for

Who it is for

Programmers who already write JavaScript - functions, objects, promises, modules - and want the type system to become a tool rather than an obstacle. No prior TypeScript is assumed. For students, for interview and exam preparation, and for working programmers who want fluency rather than a reference.

What it deliberately leaves out

No framework, no bundler, no decorators, and no test runner. A type system is easier to see without any of them in front of it. The runtime is Node and the only build tool is the compiler.

372 pages. Work the problems. That is what the book is for.