Regular Expressions 101

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/
(?:console\.(?!log))
/
gm
Non-capturing group
(?:console\.(?!log))
console
matches the characters console literally (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
Negative Lookahead
(?!log)
Assert that the Regex below does not match
log
matches the characters log literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.

Regular Expression
No Match

/
/
gm

Test String