Regular Expressions 101

^start of string

\w+any word character, repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:jpg|png|gif)

1st Alternativejpg

jpgthe literal text jpg (case sensitive)

2nd Alternativepng

pngthe literal text png (case sensitive)

3rd Alternativegif

gifthe literal text gif (case sensitive)

Non-Capturing Group(?:, \w+\.(?:jpg|png|gif)){3}

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

, the literal text ,