Regular expression for not including a word

Question

I want to create a regular expression for a string, if that string exit then it should return false.

i am using it on select option, so if value is Please select then it will be false

My impression:

^/(?!Please select)([a-z0-9]+)$

Got working expression as: /^(?!.*Please select)([a-zA-Z0-9]+)$/

I think there might be few typos (exit -> exists?), so please fix them to make your problem clearer to others... also please include relevant test cases and expected output... — Hitmands, May 22 '19 at 11:22
If you want to match it when it is not present you could use `^(?!.*Please select)[a-zA-Z0-9 ]+$`. Perhaps you could also use a form of contains if you are using code. — The fourth bird, May 22 '19 at 11:23
If `/^(?!.*Please select)([a-zA-Z0-9]+)$/` works for you why use the redundant lookahead? Use `/^[a-zA-Z0-9]+$/`. Duplicate of [RegEx for Javascript to allow only alphanumeric](https://stackoverflow.com/questions/388996). — Wiktor Stribiżew, May 22 '19 at 11:48

Jotne · Answer 1 · 2019-05-22T11:40:01.973

0

This regex should do:

^(?!.*Please select).+$

It will select all line that does not contain Please select anywhere in the line.
This will work with any character on the line, nut just letter and numbers.

edited May 22 '19 at 11:40

answered May 22 '19 at 11:25

Jotne

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This is working : /^(?!.*Please select)([a-zA-Z0-9]+)$/ – Shiv Singh May 22 '19 at 11:33
@ShivSingh No, try to add a `.` or `%` other symbol to the line with your regex. – Jotne May 22 '19 at 11:39
@Jotne Not my downvote, I believe OP just wants to match an alphanumeric string, and the lookahead is just redundant in their pattern. I'd re-close with [RegEx for Javascript to allow only alphanumeric](https://stackoverflow.com/questions/388996). Please consider casting a vote since my dupe-hammer was undone. – Wiktor Stribiżew May 22 '19 at 11:51

score 0 · Answer 2 · answered May 22 '19 at 11:55

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If you are using javascript. It will be easier and more readable to find the match and just to reverse the match result. Something like:

 let unmatched = yourLine.match(/Please select/g) == null ? true: false;

answered May 22 '19 at 11:55

Dudi Boy

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score 0 · Answer 3 · answered May 22 '19 at 12:27

This is a simple way to validate your input against presence of "Please select":

function isValid(input) {
    let regex = /Please select/;
    return !regex.test(input);
}

console.log(isValid("Please select following")); //false
console.log(isValid("selected answer!")); //true

Regular expression for not including a word

3 Answers3