Guards the value to be the Primitive type or the given type of the Primitives.

const guardPrimitive = <
  Type extends Primitive,
  Payload extends object = object
  value: Type,
  type?: Primitives,
  callback?: ResultCallback<Type, Payload>,
  payload?: Payload
): value is Type => isPrimitive(value, type, callback, payload);

Generic type variables


A generic type variable Type constrained by generic type Primitive indicates captured type of the given value via the return type and the value parameter of the provided callback function ResultCallback type.


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 guardPrimitive() function from which it captures its value.


value: Type

The value of a generic type variable Type constrained by the Primitive, by default of the type captured from itself to guard.

type?: Primitives

An optional specific type of Primitives to check the given value.

callback?: ResultCallback<Type, 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 Type

The return type is a boolean as the result of its statement indicating the value is Primitive, by default of type captured from the supplied value.


The return value is a boolean indicating whether the value is the Primitive type or the given type of Primitives.

Example usage

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

// Any primitive.
guardPrimitive('x'); // true, value is 'x'
guardPrimitive(1); // true, value is 1
guardPrimitive(true), // true, value is true
guardPrimitive(undefined); // true, value is undefined
guardPrimitive(null); // true, value is null

// string.
const firstName = 'firstName';
guardPrimitive(firstName, 'string'); // true; return type `value is "firstName"`
let letFirstName = 'firstName';
guardPrimitive(letFirstName, 'string'); // true; return type `value is string`

// number.
const age = 5;
guardPrimitive(age, 'number'); // true; return type `value is 5`
let letAge = 5;
guardPrimitive(letAge, 'number'); // true; return type `value is number`

// null.
const myNull = null;
guardPrimitive(myNull, 'null'); // true; return type `value is null`

// bigint
const oldAge = 1n;
guardPrimitive(oldAge, 'bigint'); // true; return type `value is 1n`
let letOldAge = 1n;
guardPrimitive(letOldAge, 'bigint'); // true; return type `value is bigint`

// Boolean.
const question = true;
guardPrimitive(question, 'boolean'); // true; return type `value is true`
let letQuestion = true;
guardPrimitive(letQuestion, 'boolean'); // true; return type `value is true`

// Undefined.
const und = undefined;
guardPrimitive(und, 'undefined'); // true; return type `value is undefined`
let letUndefined ;
guardPrimitive(letUndefined, 'undefined'); // true; return type `value is undefined`

// Symbol.
guardPrimitive(Symbol(firstName), 'symbol'); // true; return type `value is symbol`

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