TypeScript 3.8 will support a new import type construct. While there's already some logic for similar stuff (Flow has its own import type), TypeScript's has a few extra restrictions.

• import type can only be used on imports with named imports or with a default import - but not both.

  import type FooDefault, { Bar, Baz } from "module"; // error!

• Even though import type creates no emit, an import type functionally shadows variables from the outer scope, and using these declarations in a value position that will be emitted causes an error.

  import type { RegExp } from "special-regexp-module";
  
  // Okay - RegExp won't be used at runtime here.
  declare class Foo extends RegExp { }
  
  // Okay - RegExp won't be used at runtime here.
  let r: typeof RegExp;
  
  // Error! RegExp is imported via import type and cannot be used as a value here.
  new RegExp()

See more at

• Type-only imports and exports microsoft/TypeScript#35200
• Update type-only import semantics to allow type queries microsoft/TypeScript#36092
• Design Meeting Notes, 1/10/2020 microsoft/TypeScript#36138