Regex Always False multi Pattern-CodePudding

I am facing a weird issue with Regex. My expression working fine in https://regexr.com/3cr6f But when i use the same expression in my code then it start failing.

This is my Expression:

^([a-zA-Z] \\) (Documents){1}\\{1}((CT([A-Za-z]){0,2})|(FE)|(FF))$

I want to test this expression on my typescript string:

 var case1='User\Folders\MyDocuments\CTTV';
 var case2='User\Folders\MyDocuments\FE';
 var case3='User\Folders\MyDocuments\FF';

But it always return me null.

var regex = new RegExp(/^([a-zA-Z] \\) (Documents){1}\\{1}((CT([A-Za-z]){0,2})|(FE)|(FF))$/);
regex.test(case1); //false

Might be someone else also faced such issue in Javascript typescript.

CodePudding user response：

As pointed out by one of the comments, the test strings are MyDocuments but your regex has Documents. If you adjust your regex to this:

^([a-zA-Z] \\) (MyDocuments){1}\\{1}((CT([A-Za-z]){0,2})|(FE)|(FF))$

It works fine

https://regex101.com/r/xoGaue/1

CodePudding user response：

So the reason why it does not work at the moment is that you are trying to match the string myDocuments to Documents.

To fix your regex I would add a partial match for regex by adding .*? this will match any possible characters.

^([a-zA-Z] \\) (.*?Documents.*?){1}\\{1}((CT([A-Za-z]){0,2})|(FE)|(FF))

but I would change your regex all together:

if you do not care about the document folder then I would suggest:

^(. )\\ ((CT([A-Za-z]){0,2})|(FE)|(FF))$

else you can use:

^(. )\\ (.*?Documents.*?){1}\\((CT([A-Za-z]){0,2})|(FE)|(FF))$

see here:

https://regex101.com/r/qd4Fjs/1

CodePudding user response：

add "My" to "Documents"
use String.raw`` to escape backslash

Check it out": https://playcode.io/918676/

    let 
    case1=String.raw`User\Folders\MyDocuments\CTTV`,
    case2=String.raw`User\Folders\MyDocuments\FE`,
    case3=String.raw`User\Folders\MyDocuments\FF`,
    case4=String.raw`User\Folders\MyDocuments\False`

    let regex = new RegExp(/^([a-zA-Z] \\) (MyDocuments){1}\\{1}((CT([A-Za-z]){0,2})|(FE)|(FF))$/);
    
    console.log(
      regex.test(case1),
      regex.test(case2),
      regex.test(case3),
      regex.test(case4)
    )