ts-r
  • Error
  • Reported by the type checker

TS1433

Neither decorators nor modifiers may be applied to 'this' parameters.

A decorator or a modifier such as `public` is applied to a `this` parameter. Remove it.

What it means

A this parameter only declares the type of this inside a function. It isn't a real parameter, so it can't have decorators or modifiers like public or readonly.

Example

index.ts
declare function track(...args: unknown[]): void;

export class Counter {
  count = 0;
  increment(@track this: Counter) {
    this.count++;
  }
}
ts-r-check -p tsconfig.json --pretty false ts-r output
index.ts(5,13): error TS1433: Neither decorators nor modifiers may be applied to 'this' parameters.

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

  • Remove the modifier or decorator from this.