Answer by CodeMonkey for Not able to match the RegExp in JavaScript even it is matching in QuickRex

Best I can tell, the regex you provided, is matching exactly 1 character. the [] operator indicates "any of what is inside". But the only place you are indicating "multiple times" is the [A-Z]{1,8}. Also, as @Pointy mentioned, I don't think you can nest square brackets. Even if you can, it is somewhat redundant.