> For the complete documentation index, see [llms.txt](https://radoslaw-medryk.gitbook.io/verifica/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://radoslaw-medryk.gitbook.io/verifica/predicates/built-in-predicates/isoneof.md).

# isOneOf

```typescript
isOneOf(allowedValues)
```

Verifies if provided `Validatable` is exactly equal (`===`) to one of provided values in array `allowedValues`.

### Arguments:

* `allowedValues` - required, array of values.

### Possible errors:

#### If provided `Validatable` is not equal (`===`) to any of values in provided `allowedValues` array:

```typescript
{
    type: "isOneOf",
    path: [/* ... */]
}
```

### Examples:

Each of examples uses this import statement:

```typescript
const { asVerificable, isValid, isOneOf, getErrors } = require("verifica");
```

#### Value not equally (`===`) matching any of provided `allowedValues` :

```typescript
const verificable = asVerificable("something");
isValid(verificable, isOneOf(["a", "b", "c"])); // false
getErrors(verificable, isArrayOf(isString)); // [{ type: "isOneOf", path: [] }]
```

#### Value matching at least one of `allowedValues`:

```typescript
const verificable = asVerificable(123);
isValid(verificable, isOneOf([111, 123, 222])); // true
```


---

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