Another major addition is support for the `import defer` syntax, which allows for module evaluation to be delayed, granting developers finer control over when specific modules are executed. This feature is particularly useful for managing costly or platform-specific module initializations, ultimately improving application startup performance by deferring the loading of non-essential modules until they are needed.
TypeScript 5.9 also introduces the stable `--module node20` option, aligning with Node.js v20 standards for module and module resolution settings, ensuring consistency for future updates. Furthermore, the beta version enhances the developer experience by providing summary descriptions for various DOM APIs sourced from MDN documentation, improving accessibility to important information.
Additionally, the "quick info verbosity" feature allows developers to access more detailed type information through hover tooltips, with a new configurable maximum hover length that accommodates a richer presentation of information. The beta also optimizes cache instantiations on mappers, reducing unnecessary work and memory allocations, and prevents closure creation during file or directory existence checks.
To begin using TypeScript 5.9 Beta, developers can install it via npm with the command `npm install -D typescript@beta`.
In summary, TypeScript 5.9 Beta is a forward-thinking release that not only modernizes existing tools but also introduces new features that prioritize performance and usability, positioning it as a valuable upgrade for developers working with TypeScript. As the language continues to evolve, further enhancements and refinements are expected in future releases, which will likely focus on improving integration with emerging technologies and frameworks
TypeScript 5.9 Beta released
Microsoft has released TypeScript 5.9 Beta, which encompasses various enhancements, featuring a streamlined and modernized tsc --init flag, support for import defer, and the inclusion of the --module node20 capability. The updated tsc --init command produces a tsconfig.json file that is now more detailed and user-friendly. The newly introduced import defer syntax facilitates module evaluation without immediate execution, thereby enhancing control over the timing of work and side effects. This feature is advantageous for conditionally loading modules that require costly or platform-specific initialization. It enhances startup performance by postponing module evaluation for application features until they are genuinely required. The beta remains unaltered or "downleveled" by TypeScript and is designed for deployment in native runtimes or bundlers.
TypeScript 5.9 introduces a stable option named node20 for the --module and --moduleResolution settings, designed in accordance with Node.js v20. This option is expected to remain consistent moving forward. TypeScript now features summary descriptions for numerous DOM APIs derived from the MDN documentation. The "quick info verbosity" feature enables users to delve deeper into types within quick info tooltips. The language server offers a configurable maximum hover length, enabling a greater amount of information to be presented in hover tooltips by default. TypeScript 5.9 enhances cache instantiations on mappers, minimizing unnecessary work and allocations, while also preventing closure creation in file or directory existence checks using source.
