# guardBigInt()

## `guardBigInt()`

Guards the value to be a [`bigint`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt).

{% code title="guard-bigint.func.ts" %}

```typescript
const guardBigInt = <
  BigInt extends bigint,
  Payload extends object = object
>(
  value: BigInt,
  callback?: ResultCallback<BigInt, Payload>,
  payload?: Payload
): value is BigInt => isBigInt(value, callback, payload);
```

{% endcode %}

### Generic type variables

#### <mark style="color:green;">**`BigInt`**</mark>**`extends`**<mark style="color:green;">**`bigint`**</mark>

A generic type variable `BigInt` constrained by the [`bigint`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt) indicates captured [`bigint`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt) type of the given [`value`](#value-bigint) via the [return type](#return-type) and the [`value`](https://docs.angular-package.dev/type/type/resultcallback#value-value) parameter of the provided [`callback`](#callback-resultcallback-less-than-bigint-payload-greater-than) function [`ResultCallback`](https://docs.angular-package.dev/type/type/resultcallback) 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`](https://docs.angular-package.dev/type/type/resultcallback#payload-payload) of the supplied [`callback`](#callback-resultcallback-less-than-bigint-payload-greater-than) function and [`payload`](#payload-payload) optional parameter of the [`guardBigInt()`](#guardbigint) function from which it captures its value.

### Parameters

#### `value: BigInt`

A [`bigint`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt) type value to guard.

#### `callback?: ResultCallback<BigInt, Payload>`

The optional callback [`function`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions) of [`ResultCallback`](https://docs.angular-package.dev/type/type/resultcallback) type with parameters, the [`value`](#value-bigint) that has been checked, the [`result`](https://docs.angular-package.dev/type/type/resultcallback#result-boolean) of this check, and [`payload`](https://docs.angular-package.dev/type/type/resultcallback#payload-payload) of generic type variable [`Payload`](#payloadextendsobject-object) with optional properties from the provided [`payload`](#payload-payload), to handle them before the [`result`](https://docs.angular-package.dev/type/type/resultcallback#result-boolean) return. By default, it uses [`resultCallback()`](https://docs.angular-package.dev/type/helper/resultcallback) 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`](https://docs.angular-package.dev/type/type/resultcallback#payload-payload) of the given [`callback`](#callback-resultcallback-less-than-bigint-payload-greater-than) function.

### Return type

#### `value is BigInt`

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-bigint) is [`BigInt`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt).

### Returns

The **return value** is a [`boolean`](https://www.typescriptlang.org/docs/handbook/basic-types.html#boolean) indicating whether the [`value`](#value-bigint) is a [`bigint`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt).

## Example usage

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

guardBigInt(1n); // true, value is bigint
guardBigInt(false as any); // false, value is bigint
```