★ isTrue()


Checks if any value is a boolean type or an instance of Boolean(by using the isBoolean()) equal to true.

const isTrue = <Payload extends object>(
  value: any,
  callback: ResultCallback<any, Payload> = resultCallback,
  payload?: Payload
): value is true =>
  callback(isBoolean(value) ? value.valueOf() === true : false, 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 isTrue() 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 true

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


The return value is a boolean indicating whether the provided value is a boolean type or an instance of Boolean that is equal to true.

Example usage

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

isTrue(false); // Returns `false` as `value is true`

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