Today is TypeScript’s birthday! But this birthday is a special one – 10 years ago today, on October 1st, 2012, TypeScript was unveiled publicly for the first time. The Early Days When TypeScript...

Fixes #57693.

This PR implements variadic tuple types, i.e. the ability for tuple types to have spreads of generic types that can be replaced with actual elements through type instantiation. The PR effectively i...

We currently preserve type refinements in closures for const variables and parameters that are never targeted in assignments. With this PR we also preserve type refinements for parameters, local le...

This PR implements two new features: Template literal types, which are a form of string literals with embedded generic placeholders that can be substituted with actual string literals through type...

This PR introduces conditional types which add the ability to express non-uniform type mappings. A conditional type selects one of two possible types based on a condition expressed as a type relati...

This PR includes the following: Expansion of rest parameters with tuple types into discrete parameters. Expansion of spread expressions with tuple types into discrete arguments. Generic rest param...

With this PR we enable inference of generic function type results for generic functions that operate on other generic functions. For example: declare function pipe(ab: ...

This PR introduces a new --strictBindCallApply compiler option (in the --strict family of options) with which the bind, call, and apply methods on function objects are strongly typed and strictly c...

With this PR we reflect the effects of calls to assert(...) functions and never-returning functions in control flow analysis. We also improve analysis of the effects of exhaustive switch statements...

The way this story starts is pretty interesting: one day in the lunch room in building 25 I happened to have a chat with the great Anders Hejlsberg about compilers (yeah, it was pretty cool). One...

This PR introduces Mapped Types, a new kind of object type that maps a type representing property names over a property declaration template. In combination with index types and indexed access type...

This PR implements support for discriminated union types, inspired by suggestions in #186 and #1003. Specifically, we now support type guards that narrow union types based on tests of a discriminan...

With this PR we introduce a new strict mode, --strictOptionalProperties, in which optional properties declared without an explicit undefined in their type do not permit assigning a possibly undefin...

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For years TypeScript has strived to grow and support its community. We've seen some tremendous investment, innovation, creativity, and beauty from TypeScript developers. export type ConsistentW...

In this video Anders Hejlsberg spends some time discussing TypeScript. He starts with the reasons behind creating TypeScript (the so called elevator speech) and then moves on to some of the features...

This PR introduces control flow based type analysis for local variables and parameters as initially suggested in #2388 and prototyped in #6959. Previously, the type analysis performed for type guar...

This PR expands upon #13604 to add support for mixin classes and constructors. The PR includes type system support for the ECMAScript 2015 mixin class pattern described here and here as well as rul...

Runtime type system for IO decoding/encoding. Contribute to gcanti/io-ts development by creating an account on GitHub.

This PR implements a new --strictAny compiler option in the --strict family of options. This mode forbids unsafe conversions from any to other types. Specifically, in --strictAny mode, any is assig...