Regular Expressions 101

Explanation
Pro

\ba Unicode word boundary

Negative Lookahead(?!(?:12\d{2}|1[3-9]\d{2}|20[01]\d|2020)\b)

Non-Capturing Group(?:12\d{2}|1[3-9]\d{2}|20[01]\d|2020)

1st Alternative12\d{2}

12the literal text 12

\d{2}a Unicode decimal digit, repeated exactly 2 times

2nd Alternative1[3-9]\d{2}

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[3-9]

3-9one character from 3 (51₁₀) to 9 (57₁₀)

\d{2}a Unicode decimal digit, repeated exactly 2 times

3rd Alternative20[01]\d

20the literal text 20

Character Class[01]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da Unicode decimal digit

4th Alternative2020

2020the literal text 2020

\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(?:,(?!(?:12\d{2}|1[3-9]\d{2}|20[01]\d|2020)\b)[0-9]+)*

*repeats the group contents below any number of times:

,the literal , (44₁₀ / 54₈ / 2C₁₆)

Negative Lookahead(?!(?:12\d{2}|1[3-9]\d{2}|20[01]\d|2020)\b)

Non-Capturing Group(?:12\d{2}|1[3-9]\d{2}|20[01]\d|2020)

1st Alternative12\d{2}

12the literal text 12

\d{2}a Unicode decimal digit, repeated exactly 2 times

2nd Alternative1[3-9]\d{2}

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[3-9]

3-9one character from 3 (51₁₀) to 9 (57₁₀)

\d{2}a Unicode decimal digit, repeated exactly 2 times

3rd Alternative20[01]\d

20the literal text 20

Character Class[01]

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da Unicode decimal digit

4th Alternative2020

2020the literal text 2020

\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

Match Information

Detailed match information will be displayed here automatically.

Quick Reference

25 tokens

Regular Expression

\b(?!(?:12\d{2}|1[3-9]\d{2}|20[01]\d|2020)\b)[0-9]+(?:,(?!(?:12\d{2}|1[3-9]\d{2}|20[01]\d|2020)\b)[0-9]+)*\b

New

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

1200 till 2020