Positive Lookahead (Password) in GO
Go (RE2) can't run this pattern out of the box.
Try it in the GO tester →Why it doesn't work in GO
Go's RE2 engine doesn't support lookarounds (`(?=...)`, `(?<=...)`, etc.) — they break the linear-time matching guarantee.
Workaround
Restructure to capture the surrounding context as a group instead, or use JS / Python where lookarounds are available.
Pattern
regexGO
^(?=.*\d)(?=.*[A-Z])[A-Za-z\d]{8,}$How the pattern works
(?=.*\d) is a zero-width assertion that requires the rest of the string to contain a digit somewhere. (?=.*[A-Z]) similarly requires an uppercase letter. Neither consumes characters. [A-Za-z\d]{8,}$ then matches the actual password content (≥8 alphanumerics). Lookaheads are supported in JS and Python; Go's RE2 does NOT support them.
Examples
Input
Password1Matches
Password1
Input
weakpassNo match
—Input
ALLCAPSNODIGITNo match
—