Regular Expressions 101

Explanation
Pro

\ba Unicode word boundary

Negative Lookahead(?!\d{4}\b)

\d{4}a Unicode decimal digit, repeated exactly 4 times

\ba Unicode word boundary

Character Class[0-9]+

+matches at least one character from the set below:

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

Non-Capturing Group(?:,(?!\d{4}\b)[0-9]+)*

*repeats the group contents below any number of times:

,the literal , (44₁₀ / 54₈ / 2C₁₆)

Negative Lookahead(?!\d{4}\b)

\d{4}a Unicode decimal digit, repeated exactly 4 times

\ba Unicode word boundary

Character Class[0-9]+

+matches at least one character from the set below:

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

\ba Unicode word boundary

Global pattern flags

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

Detailed match information will be displayed here automatically.

25 tokens

\b(?!\d{4}\b)[0-9]+(?:,(?!\d{4}\b)[0-9]+)*\b

New

978,763,835,536,363 123 123,456 123456,4321 excluding the years like 

1200 till 2020

978,763,835,536,363 123 123,456 123456,4321 excluding the years like 

1200 till 2020