Regular Expressions 101

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/
(?:[^a-g]|^)m
/
gm
Non-capturing group
(?:[^a-g]|^)
1st Alternative
[^a-g]
Match a single character not present in the list below
[^a-g]
a-g matches a single character in the range between a (index 97) and g (index 103) (case sensitive)
2nd Alternative
^
^ asserts position at start of a line
m matches the character m with index 10910 (6D16 or 1558) 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

Code Generator

Generated Code

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Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report.
For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions