isError

isError :: a → Boolean

Evaluates whether the given value is of type Error

import isError from 'deep-waters/isError';

const err = new Error('foo');

isError(err); // → true
isError(anythingElse); // → false

isError, like any other type validator, is mostly used in composed validators:

import isString from 'deep-waters/isString';
import matchesPattern from 'deep-waters/matchesPattern';

const isEmail = compose(
  isString,
  matchesPattern(/^\w+([.-]?\w+)*@\w+([.-]?\w+)*(\.\w{2,3})+$/),
);

isError is built on top of ofClass validator and rely on Object.prototype.toString to check on the received value type in order to avoid typeof weird behaviours and encouraging a runtime strict type validation.