Guards the value to be null.

const guardNull = <Payload extends object>(
  value: null,
  callback?: ResultCallback<null, Payload>,
  payload?: Payload
): value is null => isNull(value, callback, payload);

Code on GitHub.

Generic type variables


The Payload generic type variable constrained by object indicates the type of optional parameter payload of the supplied callback function and payload optional parameter of the guardNull() function from which it captures its value.


value: null

The value of null type to guard.

callback?: ResultCallback<null, Payload>

The optional callback function of ResultCallback type with parameters, the value that has been checked, the result of this check, and payload of generic type variable Payload with optional properties from the provided payload, to handle them before the result return. By default, it uses resultCallback() function.

payload?: Payload

An optional object of the generic type variable Payload is assigned to the payload of the given callback function.

Return type

value is null

The return type is a boolean as the result of its statement indicating the value is null.


The return value is a boolean indicating whether the value is null.

Example usage

// Example usage.
import { guardNull } from '@angular-package/type';

guardNull(null); // true, value is null
guardNull(undefined as any); // false, value is null

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