Checks if any value is of the type obtained from its object class equal to 'string' or an object type, and an instance of String.

const isStringObject = <Payload extends object>(
  value: any,
  callback: ResultCallback<any, Payload> = resultCallback,
  payload?: Payload
): value is String =>
    (typeOf(value) === 'string' || typeof value === 'object') &&
    value instanceof String,

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 isStringObject() 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 String

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


The return value is a boolean indicating whether the provided value is an instance of String.

Example usage

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

isStringObject('age'); // Returns `false` as `value is String`
isStringObject(new String('age')) // Returns `true` as `value is String`

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