List of the most commonly used regular expressions that you should know
Regular expressions or regex are used to search for and match patterns in strings or text data. This is useful for tasks such as validating input, searching for specific words or phrases, and extracting information from text.
In this post I have tried to gather some of the most used examples, I hope you find them useful ;-)
1- Regex Email Validation
Regex pattern that matches a valid email address.
Example: name@domain.com➞ https://regex101.com/r/1sIXyA/1
/^([a-zA-Z0-9._%-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,6})*$/
2- Regex URL Validation
Regex pattern that matches a valid URL starting with http or https.
Example: https://www.domain.com➞ https://regex101.com/r/gTO9nq/1
/^(https?:\/\/)?([a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5})(:[0-9]{1,5})?(\/.*)?$/
3- Regex Dates Validation
Regex pattern that matches a valid date in different formats.
3.1- Date Format YYYY-mm-dd
Example: 2001–10-25➞ https://regex101.com/r/xZOOo9/1
/^([12]\d{3}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01]))$/
3.2- Date Format dd-mm-YYYY
Example: 25–10-2001➞ https://regex101.com/r/p4pFsm/1
/^((0[1-9]|[12]\d|3[01])-(0[1-9]|1[0-2])-[12]\d{3})$/
4- Regex Time Validation
Regex pattern that matches a valid time in different formats.
4.1- Time Format HH:mm AM/PM
Example: 11:45 PM➞ https://regex101.com/r/vq9s8Z/1
/^(1[0-2]|0?[1-9]):[0-5][0-9] (AM|PM)$/
4.1- Time Format hh:mm:ss
Example: 19:45:54➞ https://regex101.com/r/cMqbxL/1
/^(0[0-9]|1[0-9]|2[1-4]):(0[0-9]|[1-5][0-9]):(0[0-9]|[1-5][0-9])$/
5- Regex Datetime Validation
Regex pattern that matches a valid datetime.
5.1- Datetime Format YYYY-mm-dd hh:mm:ss
Example: 2001–10-25 10:59:59➞ https://regex101.com/r/GcnzIJ/1
/^([12]\d{3}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01]) (0[0-9]|1[0-9]|2[1-4]):(0[0-9]|[1-5][0-9]):(0[0-9]|[1-5][0-9]))$/
5.2- Datetime Format dd-mm-YYYY hh:mm:ss
Example: 10–11-2001 10:59:59➞ https://regex101.com/r/qfc0oc/1
/^((0[1-9]|[12]\d|3[01])-(0[1-9]|1[0-2])-[12]\d{3} (0[0-9]|1[0-9]|2[1-4]):(0[0-9]|[1-5][0-9]):(0[0-9]|[1-5][0-9]))$/
6- Regex UUID Validation
Regex pattern that matches a valid UUID (Universal Unique Identifier).
Example: 20354d7a-e4fe-47af-8ff6-187bca92f3f9 ➞ https://regex101.com/r/ESgo7B/1
/^[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}$/
7- Regex IP Address Validation
Regex pattern that matches a valid IP Address version 4 and version 6.
7.1- IPv4 address
Example: 127.3.1.1 ➞ https://regex101.com/r/6kWr5c/1
/^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$/
7.2- IPv6 address
Example: ee1a:5b37:e33f:811d:1cc8:3607:af73:1e23 ➞ https://regex101.com/r/4yy1CE/1
/^(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))$/
8- Regex File Validation
Regex pattern that matches a valid file path.
8.1- Absolute file path with extension
Example: /some/path-to-fie/resource.zip ➞ https://regex101.com/r/3jdxKY/1
/^((\/|\\|\/\/|https?:\\\\|https?:\/\/)[a-z0-9_@\-^!#$%&+={}.\/\\\[\]]+)+\.[a-z]+$/
8.2- File with extension having 3 chars
Example: resource.zip ➞ https://regex101.com/r/mRqdIg/1
/^[\w,\s-]+\.[A-Za-z]{3}$/
8.3- File with extension validation
Example: resource.png ➞ https://regex101.com/r/Rj980C/1
/^[\w,\s-]+\.(jpg|jpeg|png|gif|pdf)$/
9- Regex Password Strength Validation
Regex pattern matching a strength rules of the password.
9.1- Complex
Should have 1 lowercase letter, 1 uppercase letter, 1 number, 1 special character and be at least 8 characters long.
Example: mYpa$$word123 ➞ https://regex101.com/r/mAC0uS/1
/^(?=(.*[0-9]))(?=.*[\!@#$%^&*()\\[\]{}\-_+=~`|:;"'<>,.\/?])(?=.*[a-z])(?=(.*[A-Z]))(?=(.*)).{8,}$/
9.2- Moderate
Should have 1 lowercase letter, 1 uppercase letter, 1 number, and be at least 8 characters long.
Example: passWord123 ➞ https://regex101.com/r/7JBDjg/1
/^(?=(.*[0-9]))((?=.*[A-Za-z0-9])(?=.*[A-Z])(?=.*[a-z]))^.{8,}$/
10- Regex Slug Validation
Regex pattern that matches a valid Slug.
Example: some-valid-slug ➞ https://regex101.com/r/0Bo0eH/1
/^[a-z0-9]+(?:-[a-z0-9]+)*$/
Original published at: albertcolom.com
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