Pattern modifier

A modifier which creates a validation rule to ensure that a given string matches a regular expression pattern.

Schemas

string: Learn more

Arguments

regex - The regular expression pattern to match against
message? - A custom object with error messages to be displayed when validation fails or there are type errors

Example

import { pattern, string } from '@nordic-ui/validathor';
 
const patternRule = string([
  pattern(/^[A-Z][a-z]+$/, {
    pattern_error: "Must start with uppercase followed by lowercase letters",
  }),
]);
 
try {
  const parsedValue = patternRule.parse('Hello');
  console.log('Parsed value:', parsedValue);
} catch (error) {
  console.error('Parsing failed:', error.message);
}

Regular Expression Support

The pattern modifier supports all JavaScript regular expression features:

Flags

i - Case insensitive matching
g - Global matching (finds all matches)
m - Multiline mode
s - Dot matches newlines
u - Unicode mode
y - Sticky mode

Common Patterns

import { pattern, string } from '@nordic-ui/validathor';
 
// Alphanumeric only
const alphanumericRule = string([
  pattern(/^[a-zA-Z0-9]+$/),
]);
 
// Email validation
const emailRule = string([
  pattern(/^[^\s@]+@[^\s@]+\.[^\s@]+$/),
]);
 
// Phone number (US format)
const phoneRule = string([
  pattern(/^\d{3}-\d{3}-\d{4}$/),
]);
 
// ISO date format
const dateRule = string([
  pattern(/^\d{4}-\d{2}-\d{2}$/),
]);
 
// Hex color
const hexColorRule = string([
  pattern(/^#[0-9a-fA-F]{6}$/),
]);
 
// Strong password
const passwordRule = string([
  pattern(
    /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$/,
    { pattern_error: "Password must contain uppercase, lowercase, number and special character" }
  ),
]);
 
// Semantic version
const semverRule = string([
  pattern(/^\d+\.\d+\.\d+$/),
]);
 
// URL slug
const slugRule = string([
  pattern(/^[a-z0-9]+(?:-[a-z0-9]+)*$/),
]);

Complex Validation Examples

import { pattern, string, min, max } from '@nordic-ui/validathor';
 
// Username validation
const usernameRule = string([
  min(3),
  max(20),
  pattern(/^[a-zA-Z0-9_]+$/, {
    pattern_error: "Username can only contain letters, numbers, and underscores",
  }),
]);
 
// GitHub repository name
const repoNameRule = string([
  pattern(/^[a-zA-Z0-9._-]+$/, {
    pattern_error: "Repository name can only contain letters, numbers, dots, hyphens, and underscores",
  }),
]);
 
// Credit card CVV
const cvvRule = string([
  pattern(/^\d{3,4}$/, {
    pattern_error: "CVV must be 3 or 4 digits",
  }),
]);
 
// Time format (24-hour)
const timeRule = string([
  pattern(/^([01]\d|2[0-3]):([0-5]\d)$/, {
    pattern_error: "Time must be in HH:MM format (24-hour)",
  }),
]);

Tips

Use the ^ and $ anchors to match the entire string
Escape special regex characters with backslash: \., \*, \+, etc.
Use character classes for common patterns: \d (digits), \w (word characters), \s (whitespace)
Test your regex patterns thoroughly with various inputs
Consider using more specific modifiers (like email(), url(), uuid()) when available

Min Phone