Regex Cheatsheet

Regex Pattern 库

Copy-paste ready regular expressions for common use cases. Test before production use.

📧 EmAIl & Contact Patterns EmAIl 添加ress # Basic 验证 ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$

# More permissive (real-world) ^[^\s@]+@[^\s@]+\.[^\s@]{2,}$

Phone Numbers # US phone (123) 456-7890 or 123-456-7890 ^\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}$

# International E.164 格式化 (+1234567890) ^\+?[1-9]\d{1,14}$

URLs # URL with protocol https?://[^\s/$.?#].[^\s]

# URL (optional protocol) (https?://)?[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)+[^\s]

# DomAIn name ^a-zA-Z0-9?(\.[a-zA-Z]{2,})+$

IP 添加resses # IPv4 ^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$

# IPv6 (simplified) ^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$

📅 Date & Time Patterns Dates # YYYY-MM-DD (ISO 8601) ^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$

# MM/DD/YYYY ^(0[1-9]|1[0-2])/(0[1-9]|[12]\d|3[01])/\d{4}$

# DD/MM/YYYY ^(0[1-9]|[12]\d|3[01])/(0[1-9]|1[0-2])/\d{4}$

Times # 24-hour 格式化 (HH:MM) ^([01]\d|2[0-3]):[0-5]\d$

# 24-hour with seconds ^([01]\d|2[0-3]):[0-5]\d:[0-5]\d$

# 12-hour 格式化 (HH:MM AM/PM) ^(0?[1-9]|1[0-2]):[0-5]\d\s?(AM|PM|am|pm)$

Timestamps # ISO 8601 with timezone ^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(Z|[+-]\d{2}:\d{2})$

🔐 Password & Security Patterns Password Strength # Minimum 8 chars, at least one letter and one number ^(?=.[A-Za-z])(?=.\d).{8,}$

# Minimum 8 chars, uppercase, lowercase, number ^(?=.[a-z])(?=.[A-Z])(?=.\d).{8,}$

# Strong: 8+ chars, upper, lower, number, special ^(?=.[a-z])(?=.[A-Z])(?=.\d)(?=.[@$!%?&]).{8,}$

Common Identifiers # UUID v4 ^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$

# US Social Security Number (SSN) ^\d{3}-\d{2}-\d{4}$

# US ZIP Code ^\d{5}(-\d{4})?$

# UK Postcode ^[A-Z]{1,2}\d[A-Z\d]?\s?\d[A-Z]{2}$

📝 Text Processing Patterns Whitespace # Leading whitespace ^\s+

# TrAIling whitespace \s+$

# Multiple spaces (replace with single space) \s{2,}

# Empty lines ^\s$

Numbers # Integer (positive/negative) ^-?\d+$

# Decimal number ^-?\d+(\.\d+)?$

# Currency ($123.45) ^\$?\d{1,3}(,\d{3})(\.\d{2})?$

# Percentage (12.5%) ^\d+(\.\d+)?%$

Hex Colors # Hex color (#fff or #ffffff) ^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$

# Hex with alpha ^#([A-Fa-f0-9]{8}|[A-Fa-f0-9]{4})$

🌐 HTML & 网页 Patterns HTML Tags # Opening tag <([a-zA-Z][a-zA-Z0-9])\b[^>]>

# Closing tag )>

# Self-closing tag <([a-zA-Z][a-zA-Z0-9])\b[^>]/>

HTML Comments

CSS Classes/IDs # Class selector class="([^"])"

# ID selector id="([^"])"

Markdown # Heading level 1-6 ^#{1,6}\s.+$

# Bold text \\([^]+)\\

# Italic text \([^]+)\

# Link \[([^\]])\]\(([^)])\)

📂 File & Path Patterns File 扩展s # Image files \.(jpg|jpeg|png|gif|bmp|网页p|svg)$

# Document files \.(pdf|doc|docx|txt|xls|xlsx|ppt|pptx)$

# Code files \.(js|ts|py|java|cpp|c|h|go|rs|rb|php)$

File Paths # Unix path ^(/[^/]+)+/?$

# Windows path ^[A-Za-z]:\\([^\\]+\\)[^\\]$

# Filename (no path) [^/\\]+$

🔍 Useful Regex Constructs Lookarounds # Positive lookahead foo(?=bar) # "foo" followed by "bar"

# Negative lookahead foo(?!bar) # "foo" NOT followed by "bar"

# Positive lookbehind (?<=foo)bar # "bar" preceded by "foo"

# Negative lookbehind (?

Groups & Capture # Capture group (foo|bar)

# Non-capturing group (?:foo|bar)

# Named group (Python/JS) (?Ppattern)

# Backreference (["'])\w+\1 # Matches quoted text with same quotes

💡 Quick Reference Table Pattern Regex EmAIl ^[^\s@]+@[^\s@]+\.[^\s@]{2,}$ URL https?://[^\s/$.?#].[^\s]* IPv4 `^((25[0-5] UUID ^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$ YYYY-MM-DD ^\d{4}-\d{2}-\d{2}$ Hex color ^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$ ⚠️ 导入ant Notes Test thoroughly: Always test regex patterns with your specific data Escape properly: Different languages/engines may require different escAPIng Performance: Complex regex can be slow on large 输入s HTML parsing: Regex cannot fully 解析 HTML - use proper 解析器s when possible EmAIl 验证: No perfect emAIl regex exists - 发送 verification emAIls instead Security: Regex denial-of-服务 (ReDoS) is possible with certAIn patterns 测试 工具s https://regex101.com - Interactive 测试 with explanation https://regexr.com - Visual regex 构建器 https://www.调试gex.com - Visualize regex 状态 machines