ts-r
  • Error
  • Reported by the type checker

TS2654

Non-abstract class '{0}' is missing implementations for the following members of '{1}': {2}.

A class extends an abstract class without implementing all of its abstract members. Implement them, or mark the subclass abstract.

What it means

The base class has abstract members, and a concrete (non-abstract) subclass doesn't provide some of them. The message lists the missing members. With only one missing member, the checker uses TS2515 instead.

Example

index.ts
abstract class Shape {
  abstract area(): number;
  abstract name(): string;
}
class Square extends Shape {}
export {};
ts-r-check -p tsconfig.json --pretty false ts-r output
index.ts(5,7): error TS2654: Non-abstract class 'Square' is missing implementations for the following members of 'Shape': 'area', 'name'.

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

  • Implement every listed member in the subclass.
  • Or mark the subclass abstract and implement them further down.