Regular expressions·a MIME type

a MIME type

Matches a MIME type. It is anchored at both ends, so the whole string has to match. There are no capture groups.

Pattern
/^[a-z]+\/[a-zA-Z0-9][a-zA-Z0-9.+-]*$/
Match scope
the whole string
Capture groups
0
What it catches in the first example
text/html

Try it yourself

Type any text and the parts this expression catches are highlighted. It runs in your browser and is never sent anywhere.

text/html

1 match

Examples that match

  • text/html
  • image/svg+xml
  • application/vnd.ms-excel

Examples that do not match

  • text
  • Text/HTML
  • text//html

Other expressions in this group

How 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

Q. What is the regex for a MIME type?

^[a-z]+\/[a-zA-Z0-9][a-zA-Z0-9.+-]*$.

Q. Which strings match?

Text like text/html matches; text like text does not.

Q. Does the whole string have to match?

Yes. It is wrapped in ^ and $, so nothing but a full match passes.

Q. How 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.