> test | match | fejlfind <
// Test og fejlfind regulære udtryk med realtidsmatchning
Livematchning
Matches opdateres øjeblikkeligt, mens du skriver dit regex-mønster eller teststreng.
Visuelle resultater
Matchet tekst fremhæves direkte i din teststreng med farvede baggrunde.
Mønsterbibliotek
Hurtig indsættelse af almindelige regex-mønstre til emails, URLer, telefonnumre, IP-adresser og datoer.
// REGEX
JavaScript RegExp:
Regular expressions (regex) are patterns used to match character combinations in strings. JavaScript supports flags: g (global), i (case-insensitive), m (multiline), s (dotAll), and u (unicode).
Example:
/\\d+/g matches "abc123def456" → ["123", "456"]
Use Cases:
- >Form validation: email, phone, URL
- >Text search and replace
- >Data extraction and web scraping
- >Log file analysis
- >Input sanitization
>> FAQ
Q: What is regex?
A: A regular expression is a sequence of characters that defines a search pattern for string matching, searching, and replacing.
Q: What do flags mean?
A: g (global) finds all matches. i ignores case. m (multiline) makes ^ and $ match line starts/ends. s (dotAll) makes . match newlines. u (unicode) enables full Unicode.
Q: What are capture groups?
A: Capture groups are created with parentheses () in a regex pattern to capture matched text for later reference.
Q: Greedy vs lazy matching?
A: Greedy quantifiers (*, +, {n,}) match as much text as possible. Lazy quantifiers (*?, +?, {n,}?) match as little as possible.
Q: Common regex patterns?
A: Email: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,} | URL: https?://[^\\s]+ | IP: \\b\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\b