isString

isString :: a → Boolean

Evaluates whether the given value is of type String

import isString from 'deep-waters/isString';

isString('foo'); // → true

isString(20); // → false

isString, 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})+$/),
);

isString 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.