Regex Pattern to Match Email Addresses

A simple explanation of the email regex pattern ^[\w\.-]+@[\w\.-]+\.\w+$ and how it works.

Pattern Breakdown

^[\w\.-]+@[\w\.-]+\.\w+$

Components

Character Classes

• \w - Word characters: [a-zA-Z0-9_]
• \. - Literal dot (escaped, since . matches any char)
• - - Literal hyphen
• + - Quantifier: one or more occurrences

Examples

Valid:

• user@example.com
• john.doe@company.org
• test_email@sub.domain.com
• user-123@domain-name.net

Invalid:

• user@domain (missing TLD)
• @domain.com (missing local part)
• user@.com (missing domain)
• user name@domain.com (space not allowed)
• user@domain..com (double dot)
• user@domain.co.uk (multi-part TLD not supported)

Implementation

JavaScript

const emailRegex = /^[\w\.-]+@[\w\.-]+\.\w+$/;
emailRegex.test('user@example.com'); // true

Python

import re
email_regex = r'^[\w\.-]+@[\w\.-]+\.\w+$'
bool(re.match(email_regex, 'user@example.com'))  # True

Go

emailRegex := regexp.MustCompile(`^[\w\.-]+@[\w\.-]+\.\w+$`)
emailRegex.MatchString("user@example.com") // true

Limitations

1. Multi-part TLDs: Doesn't match .co.uk, .com.au
2. No length validation: RFC 5322 limit is 320 characters
3. No quoted strings: Doesn't support "user name"@example.com
4. No plus signs: Doesn't allow + in local part

When to Use

• Client-side form validation
• Basic format checking
• Quick validation before API calls

For production, consider RFC 5322-compliant patterns or validation libraries, and always verify emails via confirmation messages.