ts-r
  • Error
  • Reported by the type checker

TS1244

Abstract methods can only appear within an abstract class.

An abstract method is declared in a class that isn't abstract. Mark the class `abstract`, or give the method a body.

What it means

An abstract method has no body, so only an abstract class, which can't be instantiated, may declare one. A plain class with an abstract method is reported here.

Example

index.ts
export class Shape {
  abstract area(): number;
}
ts-r-check -p tsconfig.json --pretty false ts-r output
index.ts(2,3): error TS1244: Abstract methods can only appear within an abstract class.

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

  • Make the class abstract: abstract class Shape.
  • Or implement the method and drop abstract.