# TS2564: Property '…' has no initializer and is not definitely assigned in the constructor.

> A class property has no initialiser and isn't assigned in the constructor. Initialise it, assign it in the constructor, or make it optional.

## What it means

With `strictPropertyInitialization` (part of `strict`), every class property whose type doesn't
include `undefined` must get a value: an initialiser, or an assignment on every path of the
constructor.

## Example

```ts
export class Session {
  token: string;
}
```

## How to fix

- Give it an initial value: `token = ""`.
- Assign it in the constructor.
- Make it optional (`token?: string`) or include `undefined` in its type if it can be missing.

Source: https://ts-r.dev/errors/TS2564/