JavaScript

What’s New in TypeScript 3.5

At the end of May, Microsoft announced the release of TypeScript 3.5. As you know, Syncfusion loves TypeScript, and all of our Essential JS 2 suites are written in it.

That doesn’t mean the lovely people developing it don’t make mistakes. You may have noticed that a bug fix packaged with version 3.4 inadvertently created its own problems. This new bug caused the type checker suddenly to have way more work to do, which slowed it down, which slowed down everything from build times to editor operations.

Well, these things happen, and the TypeScript team hunkered down to make 3.5 even faster than 3.3 was originally for many incremental checks. As the blog post announcing the release says, compile times, code completion, and other editor operations “should be snappier” now.

The latest TypeScript version also includes a new Omit type. Instead of combining Picker and Exclude helpers to omit properties of another object, developers can just use Omit.TypeScript 3.5 also improves:

• Excess property checking in object literals.
• Union type checking.
• Type inference from generic constructors.
• Incremental builds, cutting rebuilding time by up to 68%.
• Referencing UMD global declarations, which can now be done from anywhere with the new –allowUmdGlobalAccess flag.
• Selection with a Smart Selection API that intuitively understands which text to include when the selection range is expanded.

For the complete details on the new features of TypeScript 3.5, see the previously linked blog post from the TypeScript team’s Daniel Rossenwasser at Microsoft. He says that TypeScript users can look forward to “a better experience for authoring and consuming generators, support for ECMAScript’s private fields proposal, and APIs for build tools to support fast incremental builds and projects references” in the upcoming 3.6 release.

What do you think of TypeScript 3.5’s improvements? What are you most anticipating in 3.6? Let us know in the comments below.

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Jacqueline Bieringer