TypeScript 5.5, the newest model of Microsoft’s strongly typed JavaScript variant, has arrived in beta with enhancements starting from efficiency and dimension optimizations to common expression checking.
The TypeScript 5.5 beta was launched April 25 and may be accessed via Nuget or the next command: npm -D typescript@beta. A launch candidate is due June 4, and the ultimate launch is deliberate for June 18.
TypeScript 5.5 has an extended a listing of enhancements. For efficiency and dimension, monomorphization work has been accomplished for the language service and public API. With monomorphism, the editor expertise and construct instruments utilizing the TypeScript API will get quicker, TypeScript’s authors mentioned. This was the identical work beforehand accomplished for Node and Image objects in TypeScript 5.0 to make sure that they had a constant set of properties with a constant initialization order.
TypeScript 5.5 additionally contains a vital discount in general package deal dimension. The disk footprint has been decreased from 30.2 MB to twenty.4 MB, and the packed dimension from 5.5 MB to three.7 MB. As a part of work to allow isolatedDeclarations, Microsoft has improved how usually TypeScript can straight copy enter supply code when producing declaration information.
TypeScript 5.5 introduces primary syntax checking on common expressions. Till now, TypeScript usually omitted most common expressions in code, as a result of common expressions technically have an extensible grammar and TypeScript by no means made an effort to compile common expressions to earlier variations of JavaScript. This meant widespread issues would go undiscovered in common expressions.
With TypeScript 5.5, TypeScript will now infer {that a} operate returns a sort predicate underneath sure situations. And with management movement narrowing for fixed listed accesses, TypeScript now is ready to slim expressions in for obj[key] when each obj and key are successfully fixed.
TypeScript 5.5 makes API consumption of ECMAScript modules simpler. Beforehand, if a developer was writing an ECMAScript module in Node.js, named imports weren’t obtainable from the typescript package deal. This has been mounted. TypeScript additionally now helps a brand new @import remark tag that has the identical syntax as ECMAScript imports.
TypeScript 5.5 additionally provides a transpileDeclaration API, which is designed to generate a single declaration file based mostly on enter supply textual content. The API is much like transpileModule for compiling a single file of TypeScript code.
TypeScript 5.5 follows TypeScript 5.4, which turned typically obtainable in March and introduced preserved narrowing inside operate closures.
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