Regular Expressions 101

Explanation
Pro

^start of line

Non-Capturing Group(?:\d{4}|\d{6})

1st Alternative\d{4}

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

2nd Alternative\d{6}

\d{6}a digit, repeated exactly 6 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.

26 tokens

^(?:\d{4}|\d{6})$

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