TypeScript
The official blog of the TypeScript team.
Latest posts
A 10x Faster TypeScript
Today I'm excited to announce the next steps we're taking to radically improve TypeScript performance. The core value proposition of TypeScript is an excellent developer experience. As your codebase grows, so does the value of TypeScript itself, but in many cases TypeScript has not been able to scale up to the very largest codebases. Developers working in large projects can experience long load and check times, and have to choose between reasonable editor startup time or getting a complete view of their source code. We know developers love when they can rename variables with confidence, find all referen...
Announcing TypeScript 5.8
Today we're excited to announce the release of TypeScript 5.8! If you're not familiar with TypeScript, it's a language that builds on top of JavaScript by adding syntax for types. Writing types in our code allows us to explain intent and have other tools check our code to catch mistakes like typos, issues with and , and more. Types also power TypeScript's editor tooling like the auto-completion, code navigation, and refactorings that you might see in editors like Visual Studio and VS Code. In fact, TypeScript and its ecosystem powers the JavaScript experience in both of those editors as well! To get sta...
Announcing TypeScript 5.8 RC
Today we are excited to announce the Release Candidate (RC) of TypeScript 5.8! To get started using the Release Candidate, you can get it through npm with the following command: Let's take a look at what's new in TypeScript 5.8! What's New Since the Beta? Since our beta release, we have had to pull back some work on how functions with conditional return types are checked. Based on some of the limitations and changes we wanted to make, we decided to iterate on the feature with the goal of shipping it in TypeScript 5.9. However, as part of this work, we added more granular checks for branches within return ...
Announcing TypeScript 5.8 Beta
Today we are excited to announce the availability of TypeScript 5.8 Beta. To get started using the beta, you can get it through npm with the following command: Let's take a look at what's new in TypeScript 5.8! Checked Returns for Conditional and Indexed Access Types Consider an API that presents a set of options to a user: The intent with is that it shows a UI element that can allow selecting either a single option or multiple options. When it does this is determined by the parameter. When is , the return type of should be , and when it is , the return type should be . The problem is that the typ...
Announcing TypeScript 5.7
Today we excited to announce the availability of TypeScript 5.7! If you're not familiar with TypeScript, it's a language that builds on JavaScript by adding syntax for type declarations and annotations. This syntax can be used by the TypeScript compiler to type-check our code, and it can also be erased to emit clean, idiomatic JavaScript code. Type-checking is helpful because it can catch bugs in our code ahead of time, but adding types to our code also makes it more readable and allows tools like code editors to give us powerful features like auto-completion, refactorings, find-all-references, and more. TypeScr...
Announcing TypeScript 5.7 RC
Today we are announcing the availability of the release candidate of TypeScript 5.7. To get started using the RC, you can get it through npm with the following command: Let's take a look at what's new in TypeScript 5.7! Checks for Never-Initialized Variables For a long time, TypeScript has been able to catch issues when a variable has not yet been initialized in all prior branches. Unfortunately, there are some places where this analysis doesn't work. For example, if the variable is accessed in a separate function, the type system doesn't know when the function will be called, and instead takes an "...
Announcing TypeScript 5.7 Beta
Today we are announcing the availability of TypeScript 5.7 Beta. To get started using the beta, you can get it through npm with the following command: Let's take a look at what's new in TypeScript 5.7! Checks for Never-Initialized Variables For a long time, TypeScript has been able to catch issues when a variable has not yet been initialized in all prior branches. Unfortunately, there are some places where this analysis doesn't work. For example, if the variable is accessed in a separate function, the type system doesn't know when the function will be called, and instead takes an "optimistic" ...
Announcing TypeScript 5.6
Today we're excited to announce the release of TypeScript 5.6! If you're not familiar with TypeScript, it's a language that builds on top of JavaScript by adding syntax for types. Types describe the shapes we expect of our variables, parameters, and functions, and the TypeScript type-checker can help catch issues like typos, missing properties, and bad function calls before we even run our code. Types also power TypeScript's editor tooling like the auto-completion, code navigation, and refactorings that you might see in editors like Visual Studio and VS Code. In fact, if you write JavaScript in either of th...
Announcing TypeScript 5.6 RC
Today we are excited to announce the availability of the release candidate of TypeScript 5.6. To get started using the RC, you can get it through npm with the following command: Here's a quick list of what's new in TypeScript 5.6! What's New Since the Beta? Since TypeScript 5.6 beta, we reverted a change around how TypeScript's language service searched for files. Previously the language service would keep walking up looking for every possible project file named that might contain a file. Because this could lead to opening many referenced projects, we reverted the beh...