# isPrimitive()

## `isPrimitive()`

Checks if [`any`](https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#any) value is of the generic type [`Primitive`](/type/type/primitive.md) or specific type from a given [`type`](#type-primitives) of the generic type [`Primitives`](/type/type/primitives.md).

{% code title="is-primitive.func.ts" %}

```typescript
const isPrimitive = <
  Type extends Primitive,
  Payload extends object = object
>(
  value: any,
  type?: Primitives,
  callback: ResultCallback<any, Payload> = resultCallback,
  payload?: Payload
): value is Type =>
  isStringType(type)
    ? {
        bigint: isBigInt,
        boolean: isBooleanType,
        number: isNumberType,
        null: isNull,
        string: isStringType,
        symbol: isSymbol,
        undefined: isUndefined,
      }[type](value, callback, payload)
    : callback(
        isNull(value) ||
          (typeof value !== 'object' && typeof value !== 'function'),
        value,
        payload
      );
```

{% endcode %}

### Generic type variables

#### <mark style="color:green;">`Type`</mark>`extends`<mark style="color:green;">`Primitive`</mark>

A generic type variable `Type` constrained by the generic type [`Primitive`](/type/type/primitive.md) type indicates the type of [`value`](#value-any) parameter via the [return type](#return-type) `value is Type`.

#### <mark style="color:green;">**`Payload`**</mark>**`extends`**<mark style="color:green;">**`object`**</mark>**`=`**<mark style="color:green;">**`object`**</mark>

The `Payload` generic type variable constrained by [`object`](https://www.typescriptlang.org/docs/handbook/basic-types.html#object) indicates the type of optional parameter [`payload`](/type/type/resultcallback.md#payload-payload) of the supplied [`callback`](#callback-resultcallback-less-than-any-payload-greater-than) function and [`payload`](#payload-payload) optional parameter of the [`isPrimitive()`](#isprimitive) function from which it captures its value.

### Parameters

#### `value: any`

The value of [`any`](https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#any) type to check.

#### `type?: Primitives`

An optional value of the generic type [`Primitives`](/type/type/primitives.md) type indicates against which type the provided [`value`](#value-any) is checked.

#### `callback: ResultCallback<any, Payload>`

A callback `function` of [`ResultCallback`](/type/type/resultcallback.md) type with parameters, the [`value`](#value-any) that has been checked, the [`result`](/type/type/resultcallback.md#result-boolean) of this check, and [`payload`](/type/type/resultcallback.md#payload-payload) of generic type variable [`Payload`](#payloadextendsobject-object) with optional properties from the provided [`payload`](#payload-payload), to handle them before the [`result`](/type/type/resultcallback.md#result-boolean) return. By default, it uses [`resultCallback()`](/type/helper/resultcallback.md) function.

#### `payload?: Payload`

An optional [`object`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object) of the generic type variable [`Payload`](#payloadextendsobject-object) is assigned to the [`payload`](/type/type/resultcallback.md#payload-payload) of the given [`callback`](#callback-resultcallback-less-than-any-payload-greater-than) function.

### Return type

#### `value is Type`

The **return type** is a [`boolean`](https://www.typescriptlang.org/docs/handbook/basic-types.html#boolean) as the result of its statement indicating the [`value`](#value-any) is a generic type variable [`Type`](#typeextendsprimitive) by default equal to [`Primitive`](/type/type/primitive.md).

### Returns

The **return value** is a [`boolean`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean) indicating whether the provided [`value`](#value-any) is a primitive type of the [`Primitives`](/type/type/primitives.md).

## Example usage

```typescript
// Example usage.
import { isPrimitive } from '@angular-package/type';

isPrimitive(1n); // Returns `true` as `value is Primitive`
isPrimitive<bigint>(1n, 'bigint'); // Returns `true` as `value is bigint`
isPrimitive<boolean>(false, 'boolean'); // Returns `true` as `value is boolean`
isPrimitive<number>(27, 'number'); // Returns `true` as `value is number`
isPrimitive<null>(null, 'null'); // Returns `true` as `value is null`
isPrimitive<string>('age', 'string'); // Returns `true` as `value is string`
isPrimitive<symbol>(Symbol(27), 'symbol'); // Returns `true` as `value is symbol`
isPrimitive<undefined>(undefined, 'undefined'); // Returns `true` as `value is undefined`
```


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