Regular Expressions 101

^start of line

Positive Lookahead(?=(?:.*[A-Z].*){2})

Non-Capturing Group(?:.*[A-Z].*){2}

{2}repeats the group contents below exactly 2 times:

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

Character Class[A-Z]

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

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

Negative Lookahead(?!(?:.*[A-Z].*){3,})

Non-Capturing Group(?:.*[A-Z].*){3,}

{3,}repeats the group contents below at least 3 times:

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

Character Class[A-Z]

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

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

Positive Lookahead(?=(?:.*\d.*){3})

Non-Capturing Group(?:.*\d.*){3}

{3}repeats the group contents below exactly 3 times:

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

\da digit

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

Negative Lookahead(?!(?:.*\d.*){4,})

Non-Capturing Group(?:.*\d.*){4,}

{4,}repeats the group contents below at least 4 times:

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

\da digit

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

$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.

Search reference

Regular Expression

^(?=(?:.*[A-Z].*){2})(?!(?:.*[A-Z].*){3,})(?=(?:.*\d.*){3})(?!(?:.*\d.*){4,}).*$

New

HelLo1aa2s3d: true 
WindowA1k2j3: true 
Asjs21js1: false
ASaaak12: false
AAAsjs21js1: false
AA123
AAA123
1234AA