Regular Expressions 101

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/
[a-zA-Z-0-9]+
/
gi
Match a single character present in the list below
[a-zA-Z-0-9]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case insensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case insensitive)
- matches the character - with index 4510 (2D16 or 558) literally (case insensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case insensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])
Your regular expression does not match the subject string.

Regular Expression
No Match

/
/
gi

Test String