a JWT split by two dots
Matches a JWT split by two dots. It is anchored at both ends, so the whole string has to match. There are no capture groups.
Pattern
/^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]*$/- Match scope
- the whole string
- Capture groups
- 0
- What it catches in the first example
- eyJhbGciOiJIUzI1NiJ9.eyJhIjoxfQ.sig
Try it yourself
Type any text and the parts this expression catches are highlighted. It runs in your browser and is never sent anywhere.
eyJhbGciOiJIUzI1NiJ9.eyJhIjoxfQ.sig
1 match
Examples that match
- eyJhbGciOiJIUzI1NiJ9.eyJhIjoxfQ.sig
Examples that do not match
- abc.def
- abc
Other expressions in this group
^[0-9a-f]+$a hexadecimal string^[01]+$a string of nothing but 0 and 1^[0-7]+$an octal string^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$a base64-encoded string^\+[1-9]\d{7,14}$a phone number in international form^[a-z][a-z0-9_]{2,15}$a username that starts with a letter^[a-z0-9]+(?:-[a-z0-9]+)*$a URL slug^[^\\/:*?"<>|]+\.[a-z0-9]+$a file name with an extensionHow to read this
- With ^ and $ around it, the whole string must match; without them the match can sit anywhere. Always anchor an expression you use for validation.
- Round brackets ( ) capture what they wrap. When you only need grouping, write (?: ) so the numbering of later groups does not shift.
- Every expression here is checked against its examples. Even so, "looks like an email" and "is a real inbox" remain different questions.
- Nested open-ended repeats such as (a+)+ can blow up on certain inputs. Look for that shape before pasting someone else’s expression into your code.
Frequently asked questions
QWhat is the regex for a JWT split by two dots?
^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]*$.
QWhich strings match?
Text like eyJhbGciOiJIUzI1NiJ9.eyJhIjoxfQ.sig matches; text like abc.def does not.
QDoes the whole string have to match?
Yes. It is wrapped in ^ and $, so nothing but a full match passes.
QHow do I use what it caught?
There are no capture groups, so only the whole match (match[0]) comes back. Wrap the part you need in brackets to capture it.