Again and again Regex... Can please someone show me how to got the negative lookahead working with the given regex here: https://regex101.com/r/kS6wUh/1
The Regex looks like this: ^\b[A-Z] |_ ?[A-Z]
Target would be to check if a given string contains only Characters A-Z or _
Invalid_TEXT (invalid)
all_in_small_invalid (invalid)
INVALID-DASH (invalid)
VALID_KEY (valid)
ANOTHER_VALID_KEY (valid)
(empty --> invalid)
The regex should match on invalid my current returns the valid matches.
I have no clue where to add (?!...) in my current version because all options I've tried ended up either by getting a regex error or counting everything. I think my regex has not the correct structure for a negative lookahead.
CodePudding user response：
You only have to test if one or more characters in the string are not of the set [A-Z_], which is done by inserting a caret. So [^A-Z_]. Demo
const strs = `Invalid_TEXT
all_in_small_invalid
INVALID-DASH
VALID_KEY
ANOTHER_VALID_KEY
(empty)`.split(`\n`);
strs.forEach(str => console.log(str, /[^A-Z_]/.test(str) ? `Not ok` : `OK`));