★ isFalse()

isFalse()

Checks if any value is a boolean type or an instance of Boolean by using isBoolean() function, that is equal to false.

is-false.func.ts

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

Generic type variables

Payloadextendsobject

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 isFalse() function from which it captures its value.

Parameters

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 false

The return type is a boolean as the result of its statement, indicating the value is equal to false.

Returns

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

Example usage

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

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

isFalse(new Boolean(true)); // Returns `false` as `value is false`
isFalse(new Boolean(false)); // Returns `true` as `value is false`

Parameters callback and payload

// Callback and payload parameters example usage.
import { isFalse } from '@angular-package/type';

isFalse(new Boolean(false), (result, value, payload) => {
  value // Returns `Boolean {false}`
  if (payload) {
    result // Returns `false`
    payload.age // Returns `27`
  }
  return result;
}, { age: 27 }); // Returns `true` as `value is false`