Regular Expressions 101

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/
(\[\d\])
/
g
1st Capturing Group
(\[\d\])
\[ matches the character [ with index 9110 (5B16 or 1338) literally (case sensitive)
\d matches a digit (equivalent to [0-9])
\] matches the character ] with index 9310 (5D16 or 1358) literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
g

Test String

Regex Debugger

Please wait while your expression is being debugged...