Regular Expressions 101

Sponsors
Learn to code interactively with bite-sized, hands-on programming challenges.

Community Patterns

1

ตรวจสอบพยัญชนะต้นตัวสะกดสระและวรรณยุกต์ไทย

Created·2026-01-22 01:36
Updated·2026-01-23 12:42
Flavor·JavaScript
ตรวจสอบพยัญชนะต้น (ต้องมี) ตรวจตัวสะกดสำหรับสระที่ต้องมี ตรวจสอบการวางสระและวรรณยุกต์ไทย หมายเหตุ การตรวจสอบตัวสะกดในภาษาไทยตรวจสอบได้ยากเพราะภาษาไทยเป็นภาษาที่เขียนติด ๆ กันไม่มีการแบ่งคำอย่างชัดเจนทำให้การอ่านภาษาไทยผู้อ่านต้องใช้ความหมายของคำในการตัดสินการอ่านแบ่งคำตามความเหมาะสมเช่นคำว่า "ตากลม" อาจอ่านเป็น "ตาก-ลม" ก็ได้ หรืออ่านเป็น "ตา-กลม"ก็ได้ ดังนั้นการเขียน Regex เพื่อทำการตรวจสอบอาจช่วยได้ระดับหนึ่ง อ่าจมีผิดบ้างถูกบ้าง แต่ก็ถือว่าเป็นเครื่องมือที่ใช้ช่วยเหลือในการตรวจสอบเพิ่มเติมได้ 80% ของความเป็นไปใด้ก็แล้วกันนะครับ หวังว่าการเขียนเพิ่มเติมส่วนนี้ จะมีประโยชน์บ้างไม่มากก็น้อย
Submitted by อธิปัตย์ ล้อวงศ์งาม
2

Secure Email Validation (OWASP-Aligned & DNS-Strict) (RFC 5322)

Created·2026-01-21 16:32
Updated·2026-01-21 16:36
Flavor·JavaScript
This regular expression provides a balance between RFC compliance and security-best-practices. It is designed to prevent injection vectors in legacy systems by using a restricted "safe" character subset recommended by the OWASP Validation Regex Repository. Pattern: ^A-Za-z0-9(?:\.A-Za-z0-9_+&-]+)*@(?:[A-Za-z0-9{0,61}[A-Za-z0-9])?\.)+[A-Za-z]{2,63}$ Key Features: Forced Alphanumeric Start: Prevents leading hyphens to avoid command injection vulnerabilities. Security Subset: Restricts special characters to _+&*- to prevent exotic character injections (e.g., pipes or backticks). No Quoted Strings: Forbids quoted strings to eliminate dangerous payloads containing spaces or backslashes. DNS Compliance: Enforces label lengths (1–63 characters) and prevents labels from starting or ending with hyphens. Whole String Anchoring: Uses ^ and $ to ensure the entire input is validated.
Submitted by Gor Sargsyan
1

URL, URI format validation

Created·2026-01-16 16:16
Updated·2026-01-16 23:25
Flavor·JavaScript
URL, URI format validation
Submitted by Atipat Lorwongam
2

Regex Email Format

Created·2026-01-15 17:39
Updated·2026-01-16 23:26
Flavor·JavaScript
Used to check Email Format
Submitted by Atipat Lorwongam
1

ตรวจสอบวรรณยุกต์และสระในภาษาไทย (รองรับการลากเสียงอาาาา)

Created·2026-01-15 17:20
Updated·2026-01-23 07:30
Flavor·JavaScript
ตรวจสอบการใช้วรรณยุกต์และสระในภาษาไทย รองรับการใช้สระอาาาาาติดกันแบบลากเสียง ไม่ตรวจสอบพยัญชนะต้นและตัวสะกด
Submitted by อธิปัตย์ ล้อวงศ์งาม
1

ตรวจสอบวรรณยุกต์และสระในภาษาไทย

Created·2026-01-15 17:19
Updated·2026-01-23 07:29
Flavor·JavaScript
ใช้ตรวจสอบวรรณยุกต์และสระในภาษาไทย ไม่ตรวจสอบพยัญชนะต้นและตัวสะกด
Submitted by อธิปัตย์ ล้อวงศ์งาม
1

Simple CSS Selector parser

Created·2025-12-31 14:18
Updated·2025-12-31 14:22
Flavor·JavaScript
Basic Regex for CSS Selector. Pseudo-Elements, Combinators and other advanced stuff are not supported.
Submitted by anonymous
1

Text in between HTML tags and inside quotation marks within HTML tags

Created·2025-12-08 04:32
Flavor·JavaScript
Overview This Regular Expression shows any text between HTML tags or between quotation marks within the tags themselves. An example would be: <HTML lang="en", then selecting the 'en' from there. Group 1 is between tags, and group 2 is in the quotes. I recommend only using half of this regular expression, like the 'between tags' part, or the 'inside quotes part'. Explanation The whole regex is built of two alternates, the tags and quotes part. The tags part (the first part) starts with a lookbehind of a closing of a tag, then a lazy part that selects almost characters, and a lookahead that checks for the beginning of tag (so the text is between tags). The quotes part is built in a similar structure, where it looks behind for an open of a tag, .+ , then checking for an equals sign followed by a quotation mark. The middle section of the quotes part is again just searching for text, but also not including quotation marks. The lookahead checks for a closing quotation mark and that's it! Please comment any questions or email me.
Submitted by daniel@sabian.pro
1

Universal HTML <input type="email"... requirement pattern

Created·2025-10-31 01:19
Flavor·JavaScript
This regex is a universal pattern used for the HTML input tag with type="email". Dont use type="email" as the pattern does not work with it. For the pattern to work correctly, use type="text" with inputmode="email" if you want to display the desired keyboard on mobile screens.
Submitted by kiko
1

IPv4 no leading zeros

Created·2025-10-28 09:57
Flavor·JavaScript
An IPv4 expression that doesn't allow leading zeros in octets. 10.0.0.1 will pass 10.0.0.01 shouldn't pass
Submitted by machfist
1

Only one special character("-") per word

Created·2025-09-20 18:27
Flavor·JavaScript
Only one special character ("-") is allowed when entering a word
Submitted by anonymous
1

Email validation regex

Created·2025-09-05 11:27
Flavor·JavaScript
Compliant with RFC 5322
Submitted by valentinllpz
1

Integer Number

Created·2025-08-17 13:59
Updated·2025-08-17 14:06
Flavor·JavaScript
X
Submitted by Buddha
1

op

Created·2025-07-29 00:21
Flavor·JavaScript
les
Submitted by anonymous
1

Detect age-related conversations.

Created·2025-07-21 08:50
Updated·2025-07-21 16:09
Flavor·JavaScript
Safety-measure protocol for online communities.
Submitted by mable42
1

regex for '' deletion

Created·2025-07-16 16:44
Updated·2025-07-16 16:44
Flavor·JavaScript
regex for '' deletion
Submitted by Egor K
1

Youtube URL / ID

Created·2025-05-24 02:20
Updated·2025-06-10 05:24
Flavor·JavaScript
Youtube match all URL / ID Note: Not work with rust lang if u want to use it in rust remove all the ' \ '. Regex link to watch update in the future and get data URL: https://regex101.com/r/lH4He5/
Submitted by ccauvang
1

Regex to match URLs in a string

Created·2025-05-15 02:38
Flavor·JavaScript
Regex to match URLs in a string with http and https protocol and optional paths in URL
Submitted by Kaustubh
1

https://google.com

Created·2025-04-27 00:18
Flavor·JavaScript
PropTypes.string# ``
Submitted by Khaliq88
2

BCP 47, RFC 5646, Tags for Identifying Languages

Created·2025-04-07 17:39
Flavor·JavaScript
BCP 47, RFC 5646, Tags for Identifying Languages Phillips, A., Ed., and M. Davis, Ed., "Tags for Identifying Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646, September 2009, .
Submitted by anonymous
1

Deped LRN validator

Created·2025-04-07 13:07
Flavor·JavaScript
This regex will validate a Deped's student's learner reference number (LRN) based from: https://www.teacherph.com/deped-learner-reference-number-lrn/
Submitted by anonymous
1

gdpsfh anti-stupid

Created·2025-04-05 05:32
Flavor·JavaScript
(refer to forum post 1357770511563624621) gdpsfh anti-stupid, matches correct gdps name if incorrect format https://mygdps.ps.fhgdps.com => mygdps http://mygdps.ps.fhgdps.com => mygdps https://mygdpsaaaaaaaaaaaa.ps.fhgdps.com => (no match because incorrect subdomain) correctinput => (no match)
Submitted by anonymous
1

Bangla validation regex

Created·2025-03-26 08:35
Flavor·JavaScript
আপনার কোডের Bangla validation regex শুধুমাত্র বাংলা ইউনিকোড রেঞ্জ (\u0980-\u09FF) অনুমোদন করছে। কিন্তু, "জোবায়দুল ইসলাম"-এর মধ্যে স্পেস ( ) রয়েছে, যা আপনার regex-এ অনুমোদিত নয়।** আপনার regex-টি নিচের মতো পরিবর্তন করুন, যাতে স্পেস এবং বাংলা চরিত্র উভয়ই গ্রহণযোগ্য হয়: const isBanglaText = (text: string) => { const banglaRegex = /^[\u0980-\u09FF\s]+$/; // বাংলা অক্ষর + স্পেস অনুমোদিত return banglaRegex.test(text); }; এখন "জোবায়দুল ইসলাম" এবং অন্যান্য বাংলা নাম কোনো সমস্যা ছাড়াই গ্রহণ করবে। 🚀
Submitted by Zobaidul Kazi
1

Jina AI tokenizer

Created·2025-03-05 07:59
Flavor·JavaScript
Source: X, Github
Submitted by anonymous
1

argocd-vault-plugin

Created·2025-02-14 15:39
Flavor·JavaScript
env: name: AVP_VERSION value: 1.18.0
Submitted by Yevhen Kolomeiko (Sad-Soul-Eater)
1

OGC Date-time parameter regex validator

Created·2025-02-11 08:03
Flavor·JavaScript
Many spatiotemporal OGC services use the datetime parameter to filter spatiotemporal collections. The recommended way to structure the datetime parameter is interval-closed = date-time "/" date-time interval-open-start = "../" date-time interval-open-end = date-time "/.." interval = interval-closed / interval-open-start / interval-open- end datetime = date-time / interval
Submitted by murithigeo
2

Google Analytics 4 Ecommerce Events

Created·2025-02-10 13:09
Flavor·JavaScript
gets all GA4 Ecommerce Events
Submitted by Lukas Grebe
1

Match camelCase file names. Allows numbers and [], [[]] as first chars.

Created·2025-02-06 10:38
Updated·2025-02-06 11:00
Flavor·JavaScript
This regex is used to match file names with camelCase names only. It allows numbers and [...], [[...]] as first characters.
Submitted by Florent Catiau-Tristant
1

Patu

Created·2025-02-04 08:59
Flavor·JavaScript
"^(http://|https://|http://www\.|https://www\.|www\.)?(www\.(twanda))?(([\w\-]+)?\.?(twanda|))(\.ch|\.com)(:\d+)?/.+$"igm
Submitted by anonymous
1

Instagram Profile URL

Created·2025-01-21 11:46
Flavor·JavaScript
ECMAScript for Instagram Profile URL
Submitted by chiminori
2

Telegram URL

Created·2025-01-21 10:58
Updated·2025-01-21 11:04
Flavor·JavaScript
I had to check for myself, but I thought, suddenly someone also come to someone later =)
Submitted by chiminori
1

YYMMDD Date with leap year

Created·2025-01-08 17:28
Updated·2025-02-24 07:37
Flavor·JavaScript
This expression validates any YYMMDD date, and insures that the leap year is accounted for. This is valid till 2099, 2100 is NOT a leap year.
Submitted by M. Fahmy
1

Object Value JavaScript

Created·2025-01-01 13:57
Updated·2025-01-01 14:16
Flavor·JavaScript
Get object values in javascript. Get results with "$1". Example: myObject.replace(/"(.*?)"/g, "$1")
Submitted by zazer
1

Extract & Parse URLs (Dec. 2024)

Created·2024-12-30 07:10
Flavor·JavaScript
This version has a very high accuracy - few extraneous char matches. Very verbose, heavy usage of look-aheads, look-behinds, and mostly 'inclusive' character class matching. (as opposed to the exclusion strategy in this example)
Submitted by DanLevy.net
1

Quality Value, RFC 9110 HTTP Semantics.

Created·2024-12-20 19:40
Updated·2026-01-06 22:24
Flavor·JavaScript
To extract the Quality Value (qvalue) according the RFC 9110 HTTP Semantics specifications from the weight of HTTP headers elements, like: Accept-Language Accept Accept-Charset Accept-Encoding TE weight = OWS ";" OWS "q=" qvalue qvalue = ( "0" [ "." 0*3DIGIT ] ) / ( "1" [ "." 0*3("0") ] )
Submitted by Daniel D'Leon
1

[React TypeScript] Unnecessary brackets around strings

Created·2024-12-20 13:06
Updated·2025-02-17 08:18
Flavor·JavaScript
Matches string properties that unnecessarily use brackets in React components. NOTE: If you're looking to harmonise your quote usage, use this substitution input: $1"$3$4" But be aware that strings that use single quotes inside double quotes or vice-versa will break!!!
Submitted by Nathanthanthan
1

[React TypeScript] Unnecessary backticks

Created·2024-12-20 12:55
Updated·2025-02-17 08:18
Flavor·JavaScript
Matches string properties that unnecessarily use backticks in React components. NOTE: This regex ignoes backtick strings that contain BOTH quotes (") AND single quotes (') but it WILL match backtick strings with ONLY quotes or ONLY single quotes! Keep this in mind if you want to use substitution! For example, if the string is: `prop={String with ONLY "quotes" and NO single quotes}` Then the regex will match these capture groups: $1 -> prop= $2 -> String with ONLY "quotes" and NO single quotes So if you use substitution with this input: $1"$2" You will get: prop="String with ONLY "quotes" and NO single quotes" Which will give you an error!!!
Submitted by Nathanthanthan
1

Hexadecimal

Created·2024-12-16 13:24
Flavor·JavaScript
Only matches if the entire string is in hexadecimal format
Submitted by anonymous
1

js-br

Created·2024-12-13 10:01
Flavor·JavaScript
teste
Submitted by anonymous
1

prevent double zeros

Created·2024-12-11 07:41
Flavor·JavaScript
prvent double zeros also decimals
Submitted by bilal
1

OBprefix

Created·2024-12-10 13:16
Updated·2024-12-10 13:44
Flavor·JavaScript
Frequently-used prefix regex expressions without quote form in Obsidian plugins.
Submitted by anonymous
1

quote-OBprefix

Created·2024-12-10 13:10
Updated·2024-12-10 13:43
Flavor·JavaScript
Frequently-used prefix regex expressions with quote form in Obsidian plugins.
Submitted by YaoYYoung
1

Canadian Postal Code Validation

Created·2024-11-28 18:47
Updated·2024-11-28 18:50
Flavor·JavaScript
Postal code format validation based on Canada Post Addressing Guidelines Accepts optional space or hyphens
Submitted by usrrname
1

Regex for Matching Documentation Websites

Created·2024-11-24 01:45
Flavor·JavaScript
Regex for Matching Documentation Websites This repository contains a powerful regular expression designed to match URLs that commonly point to documentation-related websites. The regex is optimized for flexibility, covering various terms and URL patterns. Regex Pattern ^.(?:\.|\/)(docs|documentation|help|guide|manual|reference|api|kb|support|resources|wiki|developer|how-to|tutorials|examples|learn|instructions)(?:\.|\/)?.$ Purpose This regex is intended to identify URLs that contain keywords associated with documentation or support websites. It handles common patterns in subdomains, directories, and file paths. Explanation ^.*: Matches any characters at the beginning of the URL (any prefix). (?:\.|\/): Matches either a period (.) or a forward slash (/) preceding the keyword. (docs|documentation|help|guide|manual|...): Matches any of the keywords listed in the group. (?:\.|\/)?: Allows an optional period (.) or forward slash (/) following the keyword. .*$: Matches any characters following the keyword (any suffix). Examples Positive Examples The following URLs should match the regex: https://example.com/docs http://docs.example.com https://example.com/documentation https://sub.domain.com/docs/index.html https://example.com/help https://api.example.com/docs http://example.com/manual/index.html https://wiki.example.com http://developer.example.com/guide https://example.com/tutorials/docs/page https://kb.example.com/docs/tutorial.html https://example.com/resources/documentation/tutorial.html http://example.com/reference/help/documentation.html https://developer.example.com/docs/tutorials/index.html http://support.example.com/documentation/overview https://resources.example.com/docs/v1/tutorial https://example.com/how-to/documentation http://example.com/api/reference/docs https://example.com/reference/v2/index.html http://example.com/docs/resources/api.html Negative Examples The following URLs should not match the regex: https://example.com/documentary http://helpful.example.com https://manuals.example.com http://example.com/references https://example.com/resourceful http://example.com/wiki-books https://apiary.example.com http://example.com/documents http://example.com/documentable https://help-center.example.com http://manual.example.com/docsystem https://example.com/resourcesful http://api.example.comary https://example.net/instructions-v1 http://example.org/learned-tutorial http://example.com/support-center Author Jeremy Georges-Filteau Website Github
Submitted by jgeofil
1

Any Unicode dash or its HTML escaped version

Created·2024-11-20 01:41
Updated·2024-11-20 01:51
Flavor·JavaScript
Match any of the weird dashes people figure out how to put in their data
Submitted by anonymous
1

test

Created·2024-11-02 23:33
Flavor·JavaScript
testing
Submitted by madgregory
1

Credit Cart Prediction & Validation

Created·2024-10-14 20:03
Updated·2024-10-16 18:23
Flavor·JavaScript
Credit Card Carrier Prediction This regex is specifically designed to predict from the first few characters which carrier type the credit card number is.
Submitted by anonymous
1

Search for markup elements with an attribute

Created·2024-10-04 19:20
Flavor·JavaScript
In this example we are searching for all element/component in JSX that have the is="secondary" prop. This regex was tested with VS Code
Submitted by anonymous
1

short IPV4 Capture

Created·2024-09-30 16:52
Flavor·JavaScript
(?(?:(?:250-5]|(?:2[0-4]|1\d|[1-9]|)\d)\.?\b){4}) Originating from ^((25[0-5]|(2[0-4]|1\d|[1-9]|)\d)\.?\b){4}$ at only 43 chars Source: [Danail Gabenski
Submitted by 0xp
1

Teste RISOLUTO button com span ícone

Created·2024-09-30 13:56
Flavor·JavaScript
Teste
Submitted by risoluto

Community Library Entry

6

Regular Expression
Created·2015-04-01 11:28
Flavor·PCRE (Legacy)

/
\A\s* (?: ######################################################################### # Option A: [<Addition to address 1>] <House number> <Street name> # # [<Addition to address 2>] # ######################################################################### (?:(?P<A_Addition_to_address_1>.*?),\s*)? # Addition to address 1 (?:No\.\s*)? (?P<A_House_number_1>\pN+[a-zA-Z]?(?:\s*[-\/\pP]\s*\pN+[a-zA-Z]?)*) # House number \s*,?\s* (?P<A_Street_name_1>(?:[a-zA-Z]\s*|\pN\pL{2,}\s\pL)\S[^,#]*?(?<!\s)) # Street name \s*(?:(?:[,\/]|(?=\#))\s*(?!\s*No\.) (?P<A_Addition_to_address_2>(?!\s).*?))? # Addition to address 2 | ######################################################################### # Option B: [<Addition to address 1>] <Street name> <House number> # # [<Addition to address 2>] # ######################################################################### (?:(?P<B_Addition_to_address_1>.*?),\s*(?=.*[,\/]))? # Addition to address 1 (?!\s*No\.)(?P<B_Street_name>\S\s*\S(?:[^,#](?!\b\pN+\s))*?(?<!\s)) # Street name \s*[\/,]?\s*(?:\sNo\.)?\s+ (?P<B_House_number>\pN+\s*-?[a-zA-Z]?(?:\s*[-\/\pP]?\s*\pN+(?:\s*[\-a-zA-Z])?)*|[IVXLCDM]+(?!.*\b\pN+\b))(?<!\s) # House number \s*(?:(?:[,\/]|(?=\#)|\s)\s*(?!\s*No\.)\s* (?P<B_Addition_to_address_2>(?!\s).*?))? # Addition to address 2 ) \s*\Z
/
x
Open regex in editor

Description

This regular expression splits an address line like for example "1117 Franklin Blvd" into the street name and house number. It also supports addresses where street name and house number are the other way around (e.g. "Mustermannstr. 1"). Furthermore, this regular expression also supports address lines where additional information is given that is neither a street name nor a house number (e.g. "3940 Radio Road, Unit 110", "Pallaswiesenstr. 57 App. 235", "Suite 1500, 802 Docklands Street"). The regular expression has 8 capture groups in total. The first 4 capture groups get used when the house number precedes the street name. The names of these capture groups are prefixed with "A_". If the house number succeeds the street name, the last 4 capture groups are used. These are prefixed with "B_".

Submitted by Andre Wisplinghoff