Checks if any value is an undefined type.

const isUndefined = <Payload extends object>(
  value: any,
  callback: ResultCallback<any, Payload> = resultCallback,
  payload?: Payload
): value is undefined => callback(typeof value === 'undefined', value, payload);

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 isUndefined() function from which it captures its value.


value: any

The value of any type to check.

callback: ResultCallback<any, Payload>

A 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 undefined

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


The return value is a boolean indicating whether the provided value is undefined.

Example usage

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

let age;
isUndefined(age); // Returns `true` as `value is undefined`
isUndefined(27); // Returns `false` as `value is undefined`

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