Question 1

What is a regular expression?

Accepted Answer

A regular expression (regex) is a sequence of characters that defines a search pattern. Regex is used in programming to find, match, and manipulate strings based on patterns rather than exact text.

Question 2

What do the regex flags mean?

Accepted Answer

g (global) finds all matches instead of stopping at the first. i (case insensitive) ignores letter case. m (multiline) makes ^ and $ match line starts/ends. s (dot all) makes the dot (.) match newlines as well.

Question 3

How do I test a regex for email addresses?

Accepted Answer

Enter a pattern like `[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}` with the g flag, paste your test string containing email addresses, and the tool will highlight all matches.

Question 4

Does this use JavaScript regex syntax?

Accepted Answer

Yes. This tool uses the browser's built-in JavaScript RegExp engine, so the syntax follows the ECMAScript (JavaScript) regular expression standard.

Regex Tester