String

Validates and transforms strings. Supports length constraints, patterns, and built-in formats like email/URL.

Chainable Methods

Method	Description	Example
.min(len)	Minimum length	.min(5)
.max(len)	Maximum length	.max(100)
.email()	Email regex	.email()
.url()	URL regex	.url()
.regex(re)	Custom RegExp	.regex(/abc/)
.trim()	Auto-trim whitespace	.trim()
.lowercase()	To lowercase	.lowercase()
.uppercase()	To uppercase	.uppercase()
.startsWith(prefix)	Prefix check	.startsWith('http')
.endsWith(suffix)	Suffix check	.endsWith('.com')
.includes(substr)	Must contain	.includes('@')
.excludes(substr)	Must not contain	.excludes('spam')
.default(val)	Fallback string	.default('anon')

Example

import { v, Infer } from 'typyn';

const emailSchema = v.string()
  .min(5)
  .max(100)
  .email()
  .trim()
  .transform((s) => s.toLowerCase());

const result = emailSchema.parse('  User@Example.COM  '); // 'user@example.com'

const safeResult = emailSchema.safe('invalid');
console.log(safeResult); // { success: false, error: { path: '', message: 'Invalid format' } }

type Email = Infer<typeof emailSchema>; // string

Error Example: Invalid email throws UnisafeError with "Invalid format".

Back to Primitives | Next: Number

---

Last updated: October 23, 2025.