ts-r
  • Error
  • Reported by the type checker

TS7009

'new' expression, whose target lacks a construct signature, implicitly has an 'any' type.

`new` is used on a value that has no construct signature, so the result would be `any`. Call a class, or type the value as a constructor.

What it means

Under noImplicitAny, calling new on something whose type has no construct signature (for example a plain function type) produces an implicit any. In TypeScript files only classes and values typed with new (...) => T can be constructed.

Example

index.ts
declare const makeUser: (name: string) => { name: string };
export const u = new makeUser("ada");
ts-r-check -p tsconfig.json --pretty false ts-r output
index.ts(2,18): error TS7009: 'new' expression, whose target lacks a construct signature, implicitly has an 'any' type.

Recorded by node scripts/verify-examples.mjs with ts-r built from commit 6deaf01. The example uses the default tsconfig: strict, target: es2022, module: esnext, moduleResolution: bundler.

How to fix

  • Call it without new if it's a plain function: makeUser("ada").
  • Turn it into a class, or give it a construct signature in its type: declare const User: new (name: string) => { name: string }.