Jump to: Regex Tester Tool
What is Regex?
Regular expressions are notations for describing patterns of text and, in effect, make up a special-purpose language for pattern matching. Although there are myriad variants, all share the idea that most characters in a pattern match literal occurrences of themselves, but some metacharacters have special meaning, such as * to indicate some kind of repetition or […] to mean any one character from the set within the brackets.
Beautiful Code by Andy Oram, Greg Wilson
More simply, Regex (short for regular expression), is a string of text that allows you to create patterns that help match, locate, and manage text.
Below is a quick reference Javascript regex cheat sheet. If you need a more in depth refresher or a place to get started I recommend these resources on regex:
Quick Reference Cheat Sheet
| Character classes | |
|---|---|
| . | any character except newline |
| \w\d\s | word, digit, whitespace |
| \W\D\S | not word, digit, whitespace |
| [abc] | any of a, b, or c |
| [^abc] | not a, b, or c |
| [a-g] | character between a & g |
| Anchors | |
| ^abc$ | start / end of the string |
| \b\B | word, not-word boundary |
| Escaped characters | |
| \.\*\\ | escaped special characters |
| \t\n\r | tab, linefeed, carriage return |
| Groups & Lookaround | |
| (abc) | capture group |
| \1 | backreference to group #1 |
| (?:abc) | non-capturing group |
| (?=abc) | positive lookahead |
| (?!abc) | negative lookahead |
| Quantifiers & Alternation | |
| a*a+a? | 0 or more, 1 or more, 0 or 1 |
| a{5}a{2,} | exactly five, two or more |
| a{1,3} | between one & three |
| a+?a{2,}? | match as few as possible |
| ab|cd | match ab or cd |
Regex Tester Tool
Disclaimer: For educational and demonstrative purposes only. Always test your regular expressions before applying anything to a production system. Results from the above tool are not guaranteed.
How To Use:
- Type a regular expression in the Regex input box. (Leading and ending slashes are added automatically)
- Type a sample string to match against in the other box.
- Check out the resulting matches.
- Tweak your regex expression until you get the expected results to test your knowledge.
