guardObjectKeyIn()

guardObjectKeyIn()

Guards the value to be an object of a generic type variable Obj that contains(or its prototype chain) the given key.

guard-object-key-in.func.ts

const guardObjectKeyIn = <
  Obj extends object,
  Key extends keyof Obj,
  Payload extends object = object
>(
  value: Obj,
  key: Key,
  callback?: ResultCallback<Obj, { key: typeof key } & Payload>,
  payload?: Payload
): value is Obj => isObjectKeyIn(value, key, callback, payload as any);

Generic type variables

Objextendsobject

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

Keyextends keyofObj

A generic type variable Key constrained by the keyof Obj, by default of value captured from the supplied key indicates the specific property name of Obj.

Payloadextendsobject=object

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 guardObjectKeyIn() function from which it captures its value.

Parameters

value: Obj

An object of a generic type variable Obj, by default of the type captured from itself that contains(or its prototype chain) the given key, to guard.

key: Key

A key of generic type variable Key as the property name that the given value contains(or its prototype chain).

callback?: ResultCallback<Obj, { key: typeof key } & 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.

The payload parameter of the callback function consists of the key property given in the key parameter, and it can't be overwritten by the given payload parameter of the main 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 Obj

The return type is a boolean as the result of its statement indicating the value is an object of a generic type variable Obj, by default of type captured from the supplied value.

Returns

The return value is a boolean indicating whether the value is an object of a generic Obj that contains(or its prototype chain) the given key.

Example usage

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

const NUMBER = 10304050;
const STRING = '!@#$%^&*()abcdefghijklmnoprstuwyz';
const SYMBOL_NUMBER: unique symbol = Symbol(NUMBER);

interface ObjectOne {
  1030405027?: string;
  [NUMBER]: number;
  [STRING]: string;
  [SYMBOL_NUMBER]?: string;
}
const OBJECT_ONE: ObjectOne = {
  1030405027: 'key is number',
  [STRING]: 'key is string',
  [SYMBOL_NUMBER]: 'key is symbol number',
  get [NUMBER](): number {
    return NUMBER;
  },
};
guardObjectKeyIn(OBJECT_ONE, 1030405027); // true, value is ObjectOne
guardObjectKeyIn(OBJECT_ONE, SYMBOL_NUMBER); // true, value is ObjectOne
guardObjectKeyIn(OBJECT_ONE, STRING); // true, value is ObjectOne
guardObjectKeyIn(OBJECT_ONE, NUMBER); // true, value is ObjectOne

// Searching in an instance of `Class`.
class Class {
  get [NUMBER](): number {
    return NUMBER;
  }
}
const CLASS = new Class();
// Getter found.
guardObjectKeyIn(CLASS, NUMBER); // true, value is Class