Regular Expressions 101

Explanation
Pro

Non-Capturing Group(?:\[\d+])+

+repeats the group contents below at least once:

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

\d+a Unicode decimal digit, repeated at least once

]the literal ] (93₁₀ / 135₈ / 5D₁₆)

$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

(?:\[\d+])+$

New

Sentences can have no index in the end.
Or one index.[10]
Or there even. Can be. Multiple sentences. And indices.[9][10][11]

Sentences can have no index in the end.
Or one index.[10]
Or there even. Can be. Multiple sentences. And indices.[9][10][11]