regex - How to check if string contains character at any point in javascript - Stack Overflow

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I need to know if a string contains a character (one or multiple times) at any point of the string. For example with the character "&":

"&hfds" is invalid, "%$/&h&" is invalid etc.

Im doing this as part of a password validation:

function applySpecialCharacterFilter(password) {
    if (password.match(/([!,%,@,#,$,^,*,?,_,~])/)) {
        return 1;
    } else if(password.match(/([&])/)) {
        throw new Error('Das Passwort enthält unerlaubte Zeichen.');
    }
    return 0;
}

in the first part it checks of the password contains any of the allowed characters, and then increments the value of the validation. But then passwords containing not allowed characters can pass. With the else if im trying to catch it, but it only works if its not in a special character sequence like $%&

Thank you

Edit:

Here is the whole function:

function checkStrength(password){
        var strength = 0;
        var passwordMessage = $('#passwordMessage');

        if (password.length == 0) {
            result.removeClass();
            return '';
        }

        if (password.length < 6) {
            validPassword = false;
            result.removeClass();
            result.addClass('short');
            return 'Too short';
        } else if(password.length > 8) {
            validPassword = false;
            result.removeClass();
            result.addClass('short');
            return 'Too long';
        } else {
            strength += 1;
        }

        try {
            strength += applyLowerAndUpperCaseFilter(password);
            strength += applyNumbersAndCharactersFilter(password);
            strength += applySpecialCharacterFilter(password);
            strength += applyTwoSpecialCharacterFilter(password);
            strength += applyAlphabeticalCharacterCriteria(password);
        } catch(error) {
            validPassword = false;
            result.removeClass();
            result.addClass('short');
            passwordMessage.html('').append('<p>TPassword contains invalid characters!</p>');
            return 'Invalid';
        }

        passwordMessage.html('');

        if (strength <= 2) {
            validPassword = false;
            result.removeClass();
            result.addClass('weak');
            return 'Schwach';
        } else if (strength <= 3 ) {
            validPassword = true;
            result.removeClass();
            result.addClass('good');
            return 'Good';
        } else {
            validPassword = true;
            result.removeClass();
            result.addClass('strong');
            return 'Strong';
        }
    }

    function applyLowerAndUpperCaseFilter(password) {
        if (password.match(/([a-z].*[A-Z])|([A-Z].*[a-z])/))
            return 1;
        return 0;
    }

    function applyNumbersAndCharactersFilter(password) {
        if (password.match(/([a-zA-Z])/) && password.match(/([0-9])/))
            return 1;
        return 0;
    }

    function applySpecialCharacterFilter(password) {
        if (password.match(/^([!%@#$^*?_~]+)$/)) {
            return 1;
        } else if(password.match(/([&])/)) {
            throw new Error('Das Passwort enthält unerlaubte Zeichen.');
        }
        return 0;
    }

    function applyTwoSpecialCharacterFilter(password) {
        if (password.match(/(.*[!,%,@,#,$,^,*,?,_,~].*[!,",%,@,#,$,^,*,?,_,~])/))
            return 1;
        else if(password.match(/([&])/))
            throw new Error('Das Passwort enthält unerlaubte Zeichen.');
        return 0;
    }

    function applyAlphabeticalCharacterCriteria(password) {
        var quality = 0;
        var sequences = [
            'abcdefghijklmnopqrstuvwxyz',
            '01234567890',
            '!\"§$%/()=?'
        ];

        var proceed = true;
        for(var i=0; i<(password.length-3); i++) {
            for(var index = 0; index < sequences.length; index++) {
                var needle = password.substring(i, 3);
                if(stripos(sequences[index], needle) != false) {
                    quality -= 1;
                    proceed = false;
                }
                if(proceed == false) break;
            }
            if(proceed == false) break;
        }
        return quality;
    }

    function stripos(f_haystack, f_needle, f_offset) {
        var haystack = (f_haystack + '')
            .toLowerCase();
        var needle = (f_needle + '')
            .toLowerCase();
        var index = 0;

        if ((index = haystack.indexOf(needle, f_offset)) !== -1) {
            return index;
        }
        return false;
    }

The messages and classes are for real time validation output only. Rules: The Password needs to be between 6 and 8 characters long.
It has to have at least 1 upper and 1 lower case character.
It has to have numbers.
It has to have at leats 1 special characters (2 give more value).
Only these special characters are allowed - _ . : , ; ! @ § $ % / = ? #
The characters should not appear in a sequence if possible, so no abc,123,!§$ etc.

I need to know if a string contains a character (one or multiple times) at any point of the string. For example with the character "&":

"&hfds" is invalid, "%$/&h&" is invalid etc.

Im doing this as part of a password validation:

function applySpecialCharacterFilter(password) {
    if (password.match(/([!,%,@,#,$,^,*,?,_,~])/)) {
        return 1;
    } else if(password.match(/([&])/)) {
        throw new Error('Das Passwort enthält unerlaubte Zeichen.');
    }
    return 0;
}

in the first part it checks of the password contains any of the allowed characters, and then increments the value of the validation. But then passwords containing not allowed characters can pass. With the else if im trying to catch it, but it only works if its not in a special character sequence like $%&

Thank you

Edit:

Here is the whole function:

function checkStrength(password){
        var strength = 0;
        var passwordMessage = $('#passwordMessage');

        if (password.length == 0) {
            result.removeClass();
            return '';
        }

        if (password.length < 6) {
            validPassword = false;
            result.removeClass();
            result.addClass('short');
            return 'Too short';
        } else if(password.length > 8) {
            validPassword = false;
            result.removeClass();
            result.addClass('short');
            return 'Too long';
        } else {
            strength += 1;
        }

        try {
            strength += applyLowerAndUpperCaseFilter(password);
            strength += applyNumbersAndCharactersFilter(password);
            strength += applySpecialCharacterFilter(password);
            strength += applyTwoSpecialCharacterFilter(password);
            strength += applyAlphabeticalCharacterCriteria(password);
        } catch(error) {
            validPassword = false;
            result.removeClass();
            result.addClass('short');
            passwordMessage.html('').append('<p>TPassword contains invalid characters!</p>');
            return 'Invalid';
        }

        passwordMessage.html('');

        if (strength <= 2) {
            validPassword = false;
            result.removeClass();
            result.addClass('weak');
            return 'Schwach';
        } else if (strength <= 3 ) {
            validPassword = true;
            result.removeClass();
            result.addClass('good');
            return 'Good';
        } else {
            validPassword = true;
            result.removeClass();
            result.addClass('strong');
            return 'Strong';
        }
    }

    function applyLowerAndUpperCaseFilter(password) {
        if (password.match(/([a-z].*[A-Z])|([A-Z].*[a-z])/))
            return 1;
        return 0;
    }

    function applyNumbersAndCharactersFilter(password) {
        if (password.match(/([a-zA-Z])/) && password.match(/([0-9])/))
            return 1;
        return 0;
    }

    function applySpecialCharacterFilter(password) {
        if (password.match(/^([!%@#$^*?_~]+)$/)) {
            return 1;
        } else if(password.match(/([&])/)) {
            throw new Error('Das Passwort enthält unerlaubte Zeichen.');
        }
        return 0;
    }

    function applyTwoSpecialCharacterFilter(password) {
        if (password.match(/(.*[!,%,@,#,$,^,*,?,_,~].*[!,",%,@,#,$,^,*,?,_,~])/))
            return 1;
        else if(password.match(/([&])/))
            throw new Error('Das Passwort enthält unerlaubte Zeichen.');
        return 0;
    }

    function applyAlphabeticalCharacterCriteria(password) {
        var quality = 0;
        var sequences = [
            'abcdefghijklmnopqrstuvwxyz',
            '01234567890',
            '!\"§$%/()=?'
        ];

        var proceed = true;
        for(var i=0; i<(password.length-3); i++) {
            for(var index = 0; index < sequences.length; index++) {
                var needle = password.substring(i, 3);
                if(stripos(sequences[index], needle) != false) {
                    quality -= 1;
                    proceed = false;
                }
                if(proceed == false) break;
            }
            if(proceed == false) break;
        }
        return quality;
    }

    function stripos(f_haystack, f_needle, f_offset) {
        var haystack = (f_haystack + '')
            .toLowerCase();
        var needle = (f_needle + '')
            .toLowerCase();
        var index = 0;

        if ((index = haystack.indexOf(needle, f_offset)) !== -1) {
            return index;
        }
        return false;
    }

The messages and classes are for real time validation output only. Rules: The Password needs to be between 6 and 8 characters long.
It has to have at least 1 upper and 1 lower case character.
It has to have numbers.
It has to have at leats 1 special characters (2 give more value).
Only these special characters are allowed - _ . : , ; ! @ § $ % / = ? #
The characters should not appear in a sequence if possible, so no abc,123,!§$ etc.

• javascript
• regex
• string

Share Improve this question Follow edited Jan 7, 2015 at 13:50 Furious Gamer asked Jan 7, 2015 at 13:36 Furious GamerFurious Gamer 53911 gold badge99 silver badges2525 bronze badges 2

• whats the rule for the invalid? – Daniel A. White Commented Jan 7, 2015 at 13:38
• only one char or multiple chars? – giammin Commented Jan 7, 2015 at 13:40

Add a ment  | 

4 Answers 4

Sorted by: Reset to default 1

You have to anchor the first regex and add a quantifier:

if (password.match(/^([!,%,@,#,$,^,*,?,_,~]+)$/)) {
//             here ^                      ^ ^

The ma is not mandatory except if you want to match it:

if (password.match(/^([!%@#$^*?_~]+)$/)) {

You can use indexOf method:

function applySpecialCharacterFilter(password) {
    if (password.indexOf('&')>-1) {
        throw new Error('Das Passwort enthält unerlaubte Zeichen.');
    }
    if (password.match(/^([!,%,@,#,$,^,*,?,_,~]+)$/)) {
        return 1;
    }
    return 0;
}

and you need to change your Regexp according @M42 answer

Here is an extremely shortened version of the password strength algorithm:

document.querySelector(".password").addEventListener("input",ev=>{
 const s=ev.target.value;
 strength=+(s.length>5&&s.length<9&&!/&/.test(s)) && 1 + // length between 6 and 8 and NO '&' in it ...
          +(/[a-z]/.test(s)&&/[A-Z]/.test(s))  // lower and upper case letters
          +(/\d/.test(s)&&/[a-z]/i.test(s))    // letters and numbers
          +/[!%@#$^*?_~]/.test(s)              // at least 1 special character
          +/(?:[!%@#$^*?_~].*){2,}/.test(s)    // at least 2 special characters
          +!s.split("").some((c,i,a)=>         // no sequence of 3 characters or more
            i>1 && s.charCodeAt(i)-s.charCodeAt(i-1)==1
                && s.charCodeAt(i-1)-s.charCodeAt(i-2)==1 )
 console.log(`${s} has a password strength of ${strength}`);
});

<input type="text" class="password">

The console will show a number from 0 to 6 indicating the password strength of the entered password.

There is no need to test for any particular invalid character. Rather, make sure your content contains nothing but valid characters and deduce that there must be an invalid character otherwise.

function applyInvalidCharacterFilter(password) {
    if (!password.match(/^[A-Za-z0-9\-_.:,;!@§\$%\/=?#]*$/)) {
         // The password contains illegal characters
         throw new Error('Das Passwort enthält unerlaubte Zeichen.');
    }
    return 0;
}

You can add the above function to your list, and remove any specific tests of whether you have the '&' character, as it would already have been caught.

Also, I would remend breaking your logic down into two steps. First, check whether the password is valid. You can treat all invalid passwords as having a strength value of zero and return an error message. Once proven valid, you can then assess the strength of a password and return a score.

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