I want to allow only specific special characters like in a text like ?*=.@#$%!^":,:;<'> -_.

I have tried the below :

  pattern = new RegExp(/^(?=.*?[?*=.@#$%!^":,:;<'> -_])/);

It does not seems to work and seems to pass even if i am entering a special character other than the ones specified above. Am i missing something here?

Eg :

var sampleText: string = "TestSample&123"

The above example should throw me an error and fail since i have not used any of the special character which is specified in the pattern.

CodePudding user response：

Based on the charset you want and the approach from this answer here about exclusive sets in Regex, you should be able to do something like this:

const testPattern = /^[?*=.@#$%!^":,;<'> \-_] $/;

console.log(testPattern.test('?* @!')); // passes
console.log(testPattern.test('TestSample&123')); // fails

CodePudding user response：

A few things:

• Javascript has regex literals, so you can do var regex = /^(?=.*?[?*=.@#$%!^":,:;<'> -_])/ instead of new Regex(...)
• https://regex101.com/ is a super helpful resource for figuring out regex. Paste ^(?=.*?[?*=.@#$%!^":,:;<'> -_]) into that site and it'll explain what each part does.
• The ^ at the beginning of the regex anchors the matching to the beginning of the string, but you don't have a corresponding $ to make sure the match applies to the entire string.
• The (?=.*? is a positive lookahead that mathces any number of any character. The character group [...] that you have is only going to match a single character, when it sounds like you want it to match all of the characters.

Rahul already answered while I was typing this up, and he's got the right expression:

^[?*=.@#$%!^":,:;<'> -_]*$

The ^ anchors the match to the beginning of the string, and the $ anchors the end of the match to the end of the string. The [...]* will match any number of characters as long as they belong to that set of characters.

You can make a JS var out this like

var myRegex = /^[?*=.@#$%!^":,:;<'> -_]*$/

CodePudding user response：

You can try to use the below regex:

    const str = /^[a-zA-Z0-9?*=.@#$%!^":,:;<'> -_] $/;
    
    console.log(str.test('TestSample&123'));