# @typescript-eslint/no-unsafe-enum-assignment

> Disallow giving a plain number or string to a place typed as an enum

The compiler accepts a plain number where a numeric enum is expected, and `as` turns a number or a string into an enum. The code then depends on the raw values behind the members, and the variable can hold a value that no `switch` over the enum handles.

The rule checks variables, assignments, default values, arguments, return values, class properties, JSX attributes, array and object literal elements, and `as` assertions. It also reports arithmetic on an enum variable, such as `current++`, and a plain number or string used as a key of an object with enum keys.

{/* Generated by src/codegen/lint-rule-docs.ts. Do not edit this section. */}

## Configure

Off by default. This rule needs types, so turning it on makes `bun lint` type check your code first.

```toml bunfig.toml
[lint.rules]
"@typescript-eslint/no-unsafe-enum-assignment" = "error" # or "warn"
```

{/* End of the generated section. */}

## Examples

Reported:

{/* bad {"count": 6} */}
```ts
enum Status {
  Open,
  Closed,
}

declare function setStatus(next: Status): void;
declare const labels: { [key in Status]: string };

let current: Status = 1;
current++;
setStatus(0);
console.log(labels[0]);
const parsed = Number("1") as Status;
const all: Status[] = [Status.Open, 1];
```

Not reported:

{/* good */}
```ts
enum Status {
  Open,
  Closed,
}

declare function setStatus(next: Status): void;
declare const labels: { [key in Status]: string };

let current: Status = Status.Closed;
current = Status.Open;
setStatus(Status.Open);
console.log(labels[Status.Open]);
const all: Status[] = [Status.Open, Status.Closed];

// This type accepts any number, so a plain number is fine.
const code: Status | number = 404;
```

Combining members of the same enum with `|`, `&`, `^` and `~` is allowed, because that's how flag enums work:

{/* good */}
```ts
enum Access {
  Read = 1,
  Write = 2,
}

let access: Access = Access.Read | Access.Write;
access &= ~Access.Write;
```

## When not to use it

Values from outside, such as JSON or a database, arrive as plain numbers and strings. If you turn them into enums with `as` in many places, this rule reports each one. If you convert them in one checked function, only that function is reported.