Callback

To handle the result of the check(before it returns) with an additional payload there is a callback function, so it is possible to, for example, send it to error tracker sentry.io or even to change the value of the result and then return.

The callback function passes the result of the check, the value that was checked, and payload with by default function name that performed the callback and some additional properties depends on the used function. Payload is changeable by the payload parameter of the parent function and also it's possible to add new properties through it.

The default callback function is used to return the result of the check.

Default resultCallback()

Default function to handle callback of ResultCallback type.

const resultCallback = (result: boolean): boolean => result;

Parameters

result: boolean

A value of boolean type of the result of the check.

Returns

The return value is a boolean of the result from the check.

Custom callback function

A custom function to handle the callback.

Example usage

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

const firstName = 'Artemis';
const additionalPayload = {
  id: 1,
  field: 'firstName',
  database: 'gods',
};

/*
  By default `callback` parameter of `isString()` function passes
  `name` and the provided `value` of `CallbackPayload` interface.
*/
const customCallback = (
  result: boolean,
  value: any,
  payload?: CallbackPayload & typeof additionalPayload
): boolean => {
  /*
    payload {
      value: 'Artemis',
      id: 1,
      field: 'firstName',
      database: 'gods'
    }
  */
  if (result === false) {
    if (payload) {
      // Send e.g. to sentry.io.
      throw new Error(`${payload.value} must be a string`);
    }
  }
  return result;
};

const stringResult = isString(firstName, customCallback, additionalPayload);

// TODO: Example usage
const customCallback = <
  Payload extends CallbackPayload<{ database?: string; id?: number }>
>(
  result: boolean,
  value: any,
  payload?: Payload
) => {
  return result;
};

isObject('x', customCallback, { database: '' });