Regular Expressions 101

Explanation
Pro

^start of line

\w+any word character, repeated at least once

Group 1(\.\w+)+

+repeats the group contents below at least once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\w+any word character, repeated at least once

$end of line

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

Detailed match information will be displayed here automatically.

25 tokens

^\w+(\.\w+)+$

New

aaa.bbb
aaa.bbb.ccc
aaa.bbb.ccc.ddd

.aaa
aaa.
.aaa.
aaa.bbb.
aaa.bbb.ccc.
aaa..bbb...ccc

aaa.bbb
aaa.bbb.ccc
aaa.bbb.ccc.ddd

.aaa
aaa.
.aaa.
aaa.bbb.
aaa.bbb.ccc.
aaa..bbb...ccc