For release notes, check out the release announcement · fixed issues query for Typescript 5.9.0 (Beta). fixed issues query for Typescript 5.9.1 (RC). No specific changes for TypeScript 5.9.2 (Stable) fixed issues query for Typescript 5.9.3 (Stable). Downloads are available on: npm ·

In TypeScript 5.8, the example code is now allowed, and the emitted declaration file will match what you wrote: ... Note that this does not create statically-named properties on the class.

This allowed us to get feedback and harden our file-watching implementation against most of these platform-specific gotchas. As TypeScript has needed to scale to larger codebases, and has improved in this area, we felt swapping to file system events as the default would be a worthwhile investment.

We also have news about our upcoming roadmap, and how we're prioritizing work on TypeScript 7.0 to drive our port to completion. Editor Support and L... ... Today we are excited to announce the release of TypeScript 5.9!

We also felt that it was time that tsc --init initialized with a few more prescriptive settings than we already enable. We looked at some common pain points and papercuts users have when they create a new TypeScript project. For example, most users write in modules (not global scripts), and --moduleDetection can force TypeScript to treat every implementation file as a module.

June 22, 2024 - As part of the work to enable isolatedDeclarations, we’ve substantially improved how often TypeScript can directly copy your input source code when producing declaration files. ... Note that the union types are equivalent, but the order of the union is different.

TypeScript 4.5 introduces a way to override a specific built-in lib in a manner similar to how @types/ support works. When deciding which lib files TypeScript should include, it will first look for a scoped @typescript/lib-* package in node_modules.

First, TypeScript 5.1 now allows undefined-returning functions to have no return statement.

We’ll also shortly be releasing a 4.9 patch to allow specifying ignoreDeprecations to allow for smoother upgrades. Aside from deprecations, we’ve changed some settings to better improve cross-platform behavior in TypeScript. --newLine, which controls the line endings emitted in JavaScript files, used to be inferred based on the current operating system if not specified. We think builds should be as deterministic as possible, and Windows Notepad ...

This section contains the release notes for all versions of TypeScript, organized chronologically from newest to oldest.

When we pass an object literal to something with an expected type, TypeScript will look for excess properties that weren’t declared in the expected type. ... A final note on index signatures is that they now permit union types, as long as they’re a union of infinite-domain primitive types - specifically:

Most of my TypeScript projects had no new errors after I updated to TS 5.5. The only exception was needing to update my target to ES2018 to get the /s regular expression flag, as described above. Both Bloomberg and Google have posted GitHub issues describing the new errors they ran into while upgrading to TS 5.5. Neither of them ran into major issues. Every new release of TypeScript is exciting, but the combination of new forms of type inference, isolatedDeclarations, and potential performance wins make this a particularly good one.

When parameters and let variables are used in non-hoisted functions, the type-checker will look for a last assignment point. If one is found, TypeScript can safely narrow from outside the containing function. What that means is the above example just works now. Note that narrowing analysis ...

March 17, 2023 - Today we’re excited to announce the release of TypeScript 5.0! This release brings many new features, while aiming to make TypeScript smaller, simpler, and faster. We’ve implemented the new decorators standard, added functionality to better ...

We initially anticipated shipping awaited in TypeScript 3.9, but as we’ve run early TypeScript builds with existing codebases, we’ve realized that the feature needs more design work before we can roll it out to everyone smoothly. As a result, we’ve decided to pull the feature out of our ...

August 1, 2025 - Note that import defer is not transformed or “downleveled” at all by TypeScript. It is intended to be used in runtimes that support the feature natively, or by tools such as bundlers that can apply the appropriate transformation.

The contents of these attributes are not checked by TypeScript since they’re host-specific, and are simply left alone so that browsers and runtimes can handle them (and possibly error). ... Dynamic import() calls can also use import attributes through a second argument. ... The expected type of that second argument is defined by a type called ImportCallOptions, which by default just expects a property called with. Note ...

TypeScript 5.7 now supports --target es2024, which allows users to target ECMAScript 2024 runtimes. This target primarily enables specifying the new --lib es2024 which contains many features for SharedArrayBuffer and ArrayBuffer, Object.groupBy, Map.groupBy, Promise.withResolvers, and more.

These release notes will list the PRs included in the release.

This made it cheap to check that super() gets called before this is referenced, but it ended up rejecting a lot of valid code. TypeScript 4.6 is now much more lenient in that check and permits other code to run before super()., all while still ensuring that super() occurs at the top-level before ...