Check if the statement description on credit card statements is valid using regular expressions

Question

Check if the statement description on credit card statements is valid using regular expressions

I need to validate a user-entered string that will be used as the description on a credit card statement to describe a purchase.

Here are the requirements:

The string must be between 5 and 22 characters long
It should have at least one letter (uppercase or lowercase)
Special characters like <, >, \, ' and " are not allowed
Only ASCII characters can be used

Currently, I have a regex pattern that partially works:

/^(?=.*?[a-zA-Z])[a-zA-Z0-9]{5,22}$/gm

This pattern correctly validates the length and ensures at least one letter is present. However, it restricts all special characters and diacritics instead of permitting only the few that are not allowed. How can I modify it to allow the specified characters?

javascript regex

Answer 1

Answer №1

To ensure a character is present, you can utilize a positive lookahead, and to prevent matching any characters specified in the character class, you can use a negative lookahead.

In the context of JavaScript, you can enable case-insensitivity by adding the flag /i and working with [a-z].

Update: As highlighted by Wiktor Stribiżew, for restricting matches to ASCII characters only, consider using [\x00-\x7F] instead of a dot.

^(?=.*[a-z])(?!.*[<>\\'"])[\x00-\x7F]{5,22}$

^ Denotes the start of the string
(?=.*[a-z]) Positive lookahead to confirm the presence of an ASCII letter
(?!.*[<>\\'"]) Negative lookahead ensures none of the characters in the class are matched
[\x00-\x7F]{5,22} Matches any ASCII character between 5 and 22 times
$ Marks the end of the string

For instance:

const regex = /^(?=.*[a-z])(?!.*[<>\\'"])[\x00-\x7F]{5,22}$/gmi;

Refer to the demonstration on regex101

Answer 2

To ensure a character is present, you can utilize a positive lookahead, and to prevent matching any characters specified in the character class, you can use a negative lookahead.

In the context of JavaScript, you can enable case-insensitivity by adding the flag /i and working with [a-z].

Update: As highlighted by Wiktor Stribiżew, for restricting matches to ASCII characters only, consider using [\x00-\x7F] instead of a dot.

^(?=.*[a-z])(?!.*[<>\\'"])[\x00-\x7F]{5,22}$

^ Denotes the start of the string
(?=.*[a-z]) Positive lookahead to confirm the presence of an ASCII letter
(?!.*[<>\\'"]) Negative lookahead ensures none of the characters in the class are matched
[\x00-\x7F]{5,22} Matches any ASCII character between 5 and 22 times
$ Marks the end of the string

For instance:

const regex = /^(?=.*[a-z])(?!.*[<>\\'"])[\x00-\x7F]{5,22}$/gmi;

Refer to the demonstration on regex101

Answer 3

Answer №2

Feel free to utilize

/^(?=[^a-z]*[a-z])(?:(?![<>\\'\"])[\x00-\x7F]){5,22}$/i
/^(?=[^a-z]*[a-z])(?![^<>\\'\"]*[<>\\'\"])[\x00-\x7F]{5,22}$/i

If you are considering allowing only printable ASCII characters, the following can be used

/^(?=[^a-z]*[a-z])(?:(?![<>\\'\"])[ -~]){5,22}$/i
/^(?=[^a-z]*[a-z])(?![^<>\\'\"]*[\lt;\gt;'"])[ -~]{5,22}$/i

Breakdown

^ - denotes the beginning of the string
(?=[^a-z]*[a-z]) - requires at least one ASCII letter in the string
```
(?:(?![<>\\'\"])[ -~]){5,22}
```
- specifies a range of five to twenty-two occurrences of any printable ASCII character excluding <, >, \', and \" (or other specified characters)
```
(?![^<>\\'\"]*[<>\\'\"])
```
- ensures that none of the excluded characters are present in the string
$ - signals the end of the string.

Answer 4

Feel free to utilize

/^(?=[^a-z]*[a-z])(?:(?![<>\\'\"])[\x00-\x7F]){5,22}$/i
/^(?=[^a-z]*[a-z])(?![^<>\\'\"]*[<>\\'\"])[\x00-\x7F]{5,22}$/i

If you are considering allowing only printable ASCII characters, the following can be used

/^(?=[^a-z]*[a-z])(?:(?![<>\\'\"])[ -~]){5,22}$/i
/^(?=[^a-z]*[a-z])(?![^<>\\'\"]*[\lt;\gt;'"])[ -~]{5,22}$/i

Breakdown

^ - denotes the beginning of the string
(?=[^a-z]*[a-z]) - requires at least one ASCII letter in the string
```
(?:(?![<>\\'\"])[ -~]){5,22}
```
- specifies a range of five to twenty-two occurrences of any printable ASCII character excluding <, >, \', and \" (or other specified characters)
```
(?![^<>\\'\"]*[<>\\'\"])
```
- ensures that none of the excluded characters are present in the string
$ - signals the end of the string.

Check if the statement description on credit card statements is valid using regular expressions

Answer №1

Answer №2

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