TypeScript Weekly

Issue #142 — June 29, 2020

Announcing TypeScript 4.0 Beta

The beta of TypeScript 4.0 is out and brings some exciting new features, including variadic tuple types, labeled tuple elements, the new assignment operators &&=, ||=, and ??=, and more.

Daniel Rosenwasser

Narrowing Types via Type Guards and Assertion Functions

Sometimes, a type is too general to be useful. This article explains how type guards and assertion functions can be used to narrow a type to a more specific one in a certain region of a program.

Dr. Axel Rauschmayer

TypeScript Types Deep Dive Part 4

The fourth part in Jaime’s video series on TypeScript’s type system. This one is about mapped types, conditional types, and the infer keyword.

Jaime González García

Improving Object.keys

How to type the Object.keys() method more accurately using a custom ObjectKeys<T> conditional type.

Stefan Baumgartner


A programming environment for TypeScript built on top of Visual Studio Code. It combines a web framework with an editor into an integrated, batteries-included solution.

Jakub Neander