Microsoft announces the release of TypeScript 5.5

Today we’re excited to announce the release of TypeScript 5.5!

If you’re not familiar with TypeScript, it’s a language that builds on top of JavaScript by making it possible to declare and describe 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 null and undefined, 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, if you write JavaScript in either of those editors, that experience is powered by TypeScript! You can learn more at the TypeScript website.

To get started using TypeScript through npm with the following command:

npm install -D typescript

or through NuGet.

Here’s a quick list of what’s new in TypeScript 5.5!

• Inferred Type Predicates
• Control Flow Narrowing for Constant Indexed Accesses
• The JSDoc @import Tag
• Regular Expression Syntax Checking
• Support for New ECMAScript Set Methods
• Isolated Declarations
• The ${configDir} Template Variable for Configuration Files
• Consulting package.json Dependencies for Declaration File Generation
• Editor and Watch-Mode Reliability Improvements
• Performance and Size Optimizations
• Easier API Consumption from ECMAScript Modules
• The transpileDeclaration API
• Notable Behavioral Changes
  • Disabling Features Deprecated in TypeScript 5.0
  • lib.d.ts Changes
  • Stricter Parsing for Decorators
  • undefined is No Longer a Definable Type Name
  • Simplified Reference Directive Declaration Emit