JavaScript Regex Pattern Library: 115 Copy-Paste Examples

Validates standard email addresses with username, @ symbol, domain, and TLD. Covers most common email formats used in web forms.

Matches US phone numbers in common formats including with/without country code, parentheses, dashes, dots, and spaces.

Validates international phone numbers following the E.164 standard. Supports 1-15 digits with optional plus prefix.

Matches HTTP and HTTPS URLs with optional www prefix, domain, path, query parameters, and fragments.

Validates IPv4 addresses ensuring each octet is 0-255. Commonly used in network tools, log analysis, and security applications.

Matches full IPv6 addresses in standard notation with 8 groups of 4 hexadecimal digits separated by colons.

Validates MAC addresses in colon or hyphen-separated format with 6 groups of 2 hexadecimal digits.

Validates domain names with proper label formatting, supporting subdomains and various TLD lengths.

Matches whole numbers including negative values. Simple pattern for validating integer input in forms or data processing.

Matches integers and decimal numbers with optional negative sign. Allows trailing decimals for flexible number parsing.

Validates US dollar amounts with optional dollar sign, comma-separated thousands, and exactly two decimal places.

Matches percentage values with optional decimal places and negative sign, requiring the percent symbol at the end.

Validates hexadecimal numbers with an optional 0x prefix. Use it for numeric hex literals; CSS color hex codes need a separate #RGB/#RRGGBB pattern.

Matches binary numbers (0s and 1s) with optional 0b prefix for standard binary notation.

Validates numbers in scientific/exponential notation like 1.5e10 or -3.14E-5. Standard format for very large or small numbers.

Validates Visa, Mastercard, Amex, and Discover card numbers by their prefix patterns and lengths. Does not verify Luhn checksum.

Validates dates in ISO 8601 format (YYYY-MM-DD) with valid month (01-12) and day (01-31) ranges.

Validates dates in US format (MM/DD/YYYY). Ensures month is 01-12 and day is 01-31.

Validates dates in day-first format common in Europe and most of the world. Day 01-31, month 01-12.

Validates 24-hour time format (HH:MM or HH:MM:SS). Hours 00-23, minutes and seconds 00-59.

Validates 12-hour time with AM/PM indicator. Hours 1-12, minutes 00-59, with flexible spacing.

Validates full ISO 8601 datetime strings with optional milliseconds and timezone offset (Z or +/-HH:MM).

Matches Unix timestamps in seconds (10 digits) or milliseconds (13 digits). Used universally in programming.

Matches relative time expressions like "5 minutes ago" or "3 months from now" for human-readable timestamps.

Validates elapsed duration strings in HH:MM:SS format with any hour count, minutes 00-59, and seconds 00-59. Use for video length, stopwatch timers, time tracking, and log duration fields.

Validates standard 5-field cron expressions (minute, hour, day, month, weekday) with wildcards and ranges.

Validates usernames with letters, numbers, underscores, and hyphens. Length 3-20 characters.

Enforces strong password policy: minimum 8 characters with at least one uppercase, lowercase, digit, and special character.

Validates URL-friendly slugs with lowercase letters, numbers, and hyphens. No consecutive or trailing hyphens.

Extracts hashtags starting with # followed by a letter and optional alphanumeric/underscore characters.

Matches opening and closing HTML tags with optional attributes. Useful for HTML manipulation and content extraction.

Matches HTML comments including multi-line content. Used for stripping comments during minification or processing.

Matches single or double-quoted strings with proper escape handling. Handles escaped quotes within strings.

Matches Markdown inline links capturing both the display text and URL. Essential for Markdown-to-HTML converters.

Matches Markdown headings H1-H6. Captures the level (number of #) and heading text.

Matches leading and trailing whitespace for trimming. Equivalent to the trim() method in most languages.

Detects consecutively repeated words like "the the" or "is is". Useful for proofreading and text cleanup.

Matches sentences starting with a capital letter and ending with period, exclamation, or question mark.

Matches JavaScript variable declarations (const, let, var) and captures the variable name.

Matches named function declarations in JavaScript, capturing the function name.

Matches 3 or 6-digit hex color codes. Commonly used to extract or validate colors from CSS stylesheets.

Matches CSS class selectors starting with a dot. Captures class names from stylesheets for analysis.

Matches Python import statements including `import` and `from...import` forms for dependency tracking.

Matches SQL SELECT queries extracting the table name from the FROM clause. Useful for query analysis and logging.

Matches JSON key-value pairs with string, number, boolean, or null values. Useful for lightweight JSON processing.

Extracts TODO, FIXME, HACK, XXX, and BUG comments from source code for task tracking.

Validates semantic version strings (SemVer) with major.minor.patch and optional pre-release and build metadata.

Matches Git commit SHA hashes in both short (7 chars) and full (40 chars) formats.

Matches environment variable assignments in KEY=VALUE format with uppercase keys and underscores.

Extracts relative import paths from JavaScript/TypeScript import and require statements.

Validates JWT (JSON Web Token) structure with three Base64URL-encoded segments separated by dots.

Validates a canonical hyphenated UUID v4/GUID string by checking the RFC 9562 version nibble (4) and variant nibble (8, 9, a, or b) in the correct positions.

Detects potential API keys and tokens in source code. Used by security tools to prevent accidental secret exposure.

Matches AWS access key IDs that always start with AKIA (long-term) or ASIA (temporary STS) followed by 16 uppercase alphanumeric characters.

Validates Base64-encoded strings with proper character set and optional padding. Used in data transfer and encoding.

Matches MD5 hash strings (32 hexadecimal characters). Used for checksums and file integrity verification.

Matches SHA-256 hash strings (64 hexadecimal characters). Standard for modern cryptographic applications.

Matches SSH public key format with algorithm prefix (rsa, ed25519, ecdsa) followed by Base64-encoded key data.

Matches JSON object patterns enclosed in curly braces. Simple detection pattern for JSON objects in text.

Matches CSV rows handling quoted fields with escaped quotes. Essential for robust CSV file processing.

Matches XML elements with opening tag, content, and matching closing tag. Captures tag name and inner content.

Matches simple YAML key-value pairs. Useful for quick parsing of configuration files.

Parses Apache/Nginx Common Log Format entries, extracting IP, timestamp, method, path, status code, and bytes.

Matches INI file section headers enclosed in square brackets. Used for parsing configuration files.

Matches TOML configuration key-value pairs. Standard format for Rust (Cargo) and Python (pyproject) projects.

Matches both single-line (--) and multi-line (/* */) SQL comments for stripping or extracting documentation.

Validates Docker image references with optional registry, tag, and digest. Used in Dockerfiles and compose files.

Matches absolute Unix/Linux file paths starting with forward slash. Validates path component characters.

Extracts email addresses from body text. Non-anchored version for finding emails within larger strings.

Extracts image source URLs from HTML img tags. Useful for web scraping, SEO image audits, and content migration.

Extracts URLs from HTML anchor tags. Essential for web crawlers, SEO tools, and broken link checkers.

Extracts content attribute values from HTML meta tags for SEO auditing and metadata analysis.

Matches inline CSS style attributes on HTML elements. Used for style extraction and converting inline styles to classes.

Extracts 11-character YouTube video IDs from various URL formats including standard, shortened, and embed URLs.

Matches Twitter/X handles with @ prefix and 1-15 alphanumeric characters or underscores.

Extracts owner and repository name from GitHub URLs. Used in dependency management and open source tooling.

Matches CSS media query declarations for responsive design. Extracts breakpoints and conditions from stylesheets.

Matches HTML5 data attributes (data-*) and captures both the attribute name and value.

Extracts file extensions from filenames. Simple pattern for file type checking in upload forms.

Matches common image file extensions including JPEG, PNG, GIF, SVG, WebP, BMP, ICO, and TIFF.

Matches common video file extensions for upload validation and media file filtering.

Validates Windows file paths with drive letter, backslash separators, and restrictions on invalid characters.

Validates MIME type format with standard top-level types and subtypes. Used in HTTP headers and file handling.

Matches S3 protocol URLs with bucket name and optional path. Used in AWS CLI commands and data engineering.

Matches US Social Security Numbers in standard XXX-XX-XXXX format. Used for PII detection and data masking.

Validates US ZIP codes in 5-digit or ZIP+4 format. Essential for shipping and address validation forms.

Matches valid US state and DC two-letter abbreviations. Complete list of all 50 states plus District of Columbia.

Validates UK postcodes in various formats (A1 1AA, A11 1AA, AA1 1AA, etc.) with optional space.

Validates Canadian postal codes in A1A 1A1 format alternating letters and digits with optional space.

Matches common passport number formats with 1-2 letter prefix followed by 6-9 digits.

Validates International Bank Account Numbers with country code, check digits, bank code, and account number.

Validates 17-character Vehicle Identification Numbers excluding I, O, and Q which can be confused with 1 and 0.

Matches innermost balanced parentheses groups. Note: regex alone cannot match nested groups — use recursive patterns or parsers.

Demonstrates positive lookahead: matches a word only if followed by " is". Lookaheads check without consuming characters.

Demonstrates positive lookbehind: matches numbers only when preceded by $. Extracts prices without the dollar sign.

Demonstrates named capture groups for readable regex. Access matches by name instead of index for clearer code.

Shows non-greedy (lazy) matching with +? quantifier. Matches shortest possible string instead of longest.

Simulates atomic groups in JavaScript using lookahead with backreference. Prevents catastrophic backtracking.

Uses alternation within non-capturing group to match URLs with HTTP, HTTPS, or FTP protocols.

Matches comma-separated email lists. Demonstrates pattern repetition for parsing delimited sequences.

Detects common SQL injection attack patterns including OR-based, UNION, and command injection.

Validates Docker image references including registry, repository, tag, and digest components.

Validates Kubernetes resource names: lowercase alphanumeric with hyphens, max 63 characters.

Validates Mastercard numbers starting with 51-55 or 2221-2720 in 16-digit format.

Validates Visa card numbers starting with 4, supporting 13 or 16 digit formats.

Matches ISO 8601 timestamps commonly found in application and system log files.

Detect common SQL injection attempts

Match standard log level keywords

Match semantic versioning strings

Match Terraform resource references

Match GraphQL operation definitions

Match GitHub repository URLs

Match valid npm package names

Match Docker image names with tags

Match KEY=value environment variable format