Regular Expressions 101

Group 1(youtube|you_other_url_format)

1st Alternativeyoutube

youtubethe literal text youtube (case insensitive)

2nd Alternativeyou_other_url_format

you_other_url_formatthe literal text you_other_url_format (case insensitive)

.*?any character (except for line terminators), repeated any number of times

Non-Capturing Group(?:[\/]|v=)

1st Alternative[\/]

Character Class[\/]

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

2nd Alternativev=

v=the literal text v= (case insensitive)

Group 2([a-zA-Z0-9-_]{11})

Character Class[a-zA-Z0-9-_]{11}

{11}matches exactly 11 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

A-Zone character from A (65₁₀) to Z (90₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(youtube|you_other_url_format).*?(?:[\/]|v=)([a-zA-Z0-9-_]{11})

New

http://www.youtube.com/watch?v=jhjhkum-kq8&feature=related
https://www.youtube.com/watch?list=RDfRh_vgS2dFE&v=fRh_vgS2dFE
https://www.youtube.com/watch?v=fRh_vgS2dFE&list=RDfRh_vgS2dFE
https://www.youtube.com/embed/NMKkz9uRXJc

Regular Expression

Substitution