Regular Expressions 101

1st Alternative(\[(img|\w{4,})\][\s\S]*?\[\/\2\])(\n?)

Group 1(\[(img|\w{4,})\][\s\S]*?\[\/\2\])

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Group 2(img|\w{4,})

1st Alternativeimg

imgthe literal text img (case insensitive)

2nd Alternative\w{4,}

\w{4,}any word character, repeated at least 4 times

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

Character Class[\s\S]*?

*?matches any number of characters from the set below:

\sany whitespace character

\Sany non-whitespace character

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

\2the text saved by group 2

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

Group 3(\n?)

\n?optionally matches a line-feed (newline) character (ASCII 10)

2nd Alternative([\s\S]+?)(\n?)(?=$|\[(?:img|\w{4,})\])

Group 4([\s\S]+?)

Character Class[\s\S]+?

+?matches at least one character from the set below:

\sany whitespace character

\Sany non-whitespace character

Group 5(\n?)

\n?optionally matches a line-feed (newline) character (ASCII 10)

Positive Lookahead(?=$|\[(?:img|\w{4,})\])

1st Alternative$

$end of string, or before its final line terminator

2nd Alternative\[(?:img|\w{4,})\]

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Non-Capturing Group(?:img|\w{4,})

1st Alternativeimg

imgthe literal text img (case insensitive)

2nd Alternative\w{4,}

\w{4,}any word character, repeated at least 4 times

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

Global pattern flags

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

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

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25 tokens

Regular Expression

(\[(img|\w{4,})\][\s\S]*?\[\/\2\])(\n?)|([\s\S]+?)(\n?)(?=$|\[(?:img|\w{4,})\])

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