TypeScript Adds Unused Span Reporting
Written by Kay Ewbank   
Thursday, 07 June 2018

The latest release of TypeScript is now available with improvements to the editor including support for unused span reporting; the ability to convert properties to getter/setter; and the choice of moving declarations to their own new files.

TypeScript was developed by Microsoft, and is a superset of JavaScript that builds on the ECMAScript standard and includes support for static types. Your TypeScript code then gets transformed into clean, runnable JavaScript. TypeScript includes editor support for Visual Studio 2015 and 2017, Sublime Text 3 and from the next release, Visual Studio Code.

The support for unused span reporting in TypeScript 2.9.1 means that unused declarations will now be highlighted. Just how they'll show up will depend on the editor you use - Visual Studio Code will display the unused part as grayed out text. The addition has been made to provide a less draconian alternative to throwing an error when declarations are found to be unused, which is what happens if you use either of the lint-like flags: --noUnusedLocals and --noUnusedParameters.

unused span reporting

The next improvement has been, according to the developers, the subject of much community demand. Two refactorings mean that you can now move declarations to their own new files, and you can also rename files within your project while keeping import paths up-to-date. 

This version also has a new feature that means you can reference a type in another module without including an import at the top of the file. In addition to avoiding the need for the reference, the new feature means you'll be able to do things such as referencing a type within a module in the global scope. Until now this wasn't possible because a file with any imports or exports is considered a module, so adding an import for a type in a global script file will automatically turn that file into a module.

The new version introduces a new import(...) type syntax. This is similar to ECMAScript’s proposed import(...) expressions. Import types use the same syntax, and provide a way to reference the type of a module, or the types which a module contains.

Other language changes mean that TypeScript’s --pretty mode is now the default when TypeScript can reasonably detect that it’s printing output to a terminal; and TypeScript is now able to import JSON files as input files when using the node strategy for moduleResolution. This means you can use json files as part of their project, and they’ll be well-typed.


More Information

TypeScript on NuGet

TypeScript On GitHub

Related Articles

TypeScript Adds Conditional Types

TypeScript 2.7 Improves Type Inference

TypeScript 2.5 Adds Optional Catch Binding

TypeScript 2.4 Adds Dynamic Import Expressions  

TypeScript 2.3 Released

TypeScript 2.2 Adds More Code Actions


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Last Updated ( Thursday, 07 June 2018 )