TS2680

error TS2680: A ‘this’ parameter must be the first parameter.

Broken Code ❌

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type Person = {
  name: string;
};

export function sayHello(text: string = 'Hello', this: Person): void {
  console.log(`${text} ${this.name}`);
}

Fixed Code ✔️

TypeScript requires that a this parameter always comes first in the list of parameters:

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type Person = {
  name: string;
};

export function sayHello(this: Person, text: string = 'Hello'): void {
  console.log(`${text} ${this.name}`);
}