Regular Expressions 101

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/
(?<!\w)\w+(?!\w)
/
g
Negative Lookbehind
(?<!\w)
Assert that the Regex below does not match
\w matches any word character (equivalent to [a-zA-Z0-9_])
\w
matches any word character (equivalent to [a-zA-Z0-9_])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
Negative Lookahead
(?!\w)
Assert that the Regex below does not match
\w matches any word character (equivalent to [a-zA-Z0-9_])
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

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