20 Essential Regular Expressions for Everyday Validation Tasks

Regular expressions (regex) are powerful text‑processing tools that enable concise and efficient implementation of complex validation logic.

1. Validate Password Strength

The password must be a combination of uppercase and lowercase letters and digits, exclude special characters, and be 8‑10 characters long.

2. Validate Chinese Characters

The string must consist solely of Chinese characters.

3. Alphanumeric or Underscore String

A string composed of digits, the 26 English letters, or underscores.

4. Validate E‑Mail Address

Standard regex for checking email address compliance.

5. Validate ID Card Number

Regex for Chinese ID numbers, supporting both 15‑ and 18‑digit formats.

6. Validate Date (yyyy‑mm‑dd)

Regex that checks dates in the "yyyy‑mm‑dd" format, accounting for leap years.

7. Validate Monetary Amount

Amount validation accurate to two decimal places.

8. Validate Mobile Phone Number

Regex for domestic phone numbers starting with 13, 15, or 18 (extendable for other prefixes).

9. Detect IE Version

Regex for checking Internet Explorer versions to handle compatibility.

10. Validate IPv4 Address

Standard regex for IPv4 addresses.

11. Validate IPv6 Address

Standard regex for IPv6 addresses.

12. Check URL Prefix

Regex to extract the protocol prefix (http or https) from a URL for further logic.

13. Extract URLs from Text

Regex that finds URLs within a block of text.

14. Validate File Path and Extension

Regex for Windows file paths and specific extensions (e.g., .txt).

15. Extract Color Hex Codes

Regex to capture hexadecimal color codes from web pages.

16. Extract Images from Web Pages

Regex for pulling all image URLs from HTML content.

17. Extract Hyperlinks

Regex to find anchor tags and retrieve hyperlink URLs.

18. Find CSS Properties

Regex that matches specific CSS property declarations.

19. Extract Comments

Regex for removing HTML comments from source code.

20. Match HTML Tags

Regex that captures HTML tag attributes.

Regular Expression Syntax Cheat Sheet

A handy cheat sheet summarizing common regex syntax for quick reference.

Learning Regular Expressions

A recommended guide for beginners who want to deepen their understanding of regex.