"Utilize Regular Expressions to conceal part of a text string with a

Question

"Utilize Regular Expressions to conceal part of a text string with a

Looking for a way to conceal part of a string using JavaScript?

For example, wanting to mask the second and third segments of a credit card number like this using regex:

4567 6365 7987 3783 → 4567 **** **** 3783
3457 732837 82372 → 3457 ****** 82372

The goal is to retain only the first 4 digits and the last 5 characters.

Here's what I've tried so far: /(?!^.*)[^a-zA-Z\s](?=.{5})/g

https://regex101.com/r/ZBi54c/2

javascript regex mask credit-card

Answer 1

Answer №1

If you're looking to mask a credit card number, here's a simple solution:

const creditCardNumber = '1234 5678 9101 1121';
const firstFour = creditCardNumber.substring(0, 4);
const lastFour = creditCardNumber.substring(creditCardNumber.length - 4);

const maskedNumbers = creditCardNumber.substring(4, creditCardNumber.length - 4).replace(/\d/g,"*");
console.log(firstFour + maskedNumbers + lastFour);

Answer 2

If you're looking to mask a credit card number, here's a simple solution:

const creditCardNumber = '1234 5678 9101 1121';
const firstFour = creditCardNumber.substring(0, 4);
const lastFour = creditCardNumber.substring(creditCardNumber.length - 4);

const maskedNumbers = creditCardNumber.substring(4, creditCardNumber.length - 4).replace(/\d/g,"*");
console.log(firstFour + maskedNumbers + lastFour);

Answer 3

Answer №2

You can take the first four digits and substitute the remaining ones.

console.log(
    ['4567 6365 7987 3783', '3457 732837 82372'].map(
        s => s.slice(0, 4) + s.slice(4).replace(/\d(?=.* )/g, '*')
    )
);

Answer 4

You can take the first four digits and substitute the remaining ones.

console.log(
    ['4567 6365 7987 3783', '3457 732837 82372'].map(
        s => s.slice(0, 4) + s.slice(4).replace(/\d(?=.* )/g, '*')
    )
);

Answer 5

Answer №3

The original poster seems satisfied with the answer provided. I have come up with an alternative solution that utilizes just regular expressions:

function maskNumbers(match, group1, group2, group3) {
  var maskedNums = group2.replace(/\d/g, '*');
  return group1 + " " + maskedNums + " " + group3;
}

function maskCreditCardNumbers(str) {
  var regex = /(\d{4})\s(\d{4}\s\d{4}|\d{6})\s(\d{4}|\d{5})/;

  if (regex.test(str))
    return str.replace(regex, maskNumbers);
  else return "";
}


var cardNumber1 = "4567 6365 7987 3783";
var cardNumber2 = "3457 732837 82372";
var textString = "dfdf dfdf";
console.log(maskCreditCardNumbers(cardNumber1));
console.log(maskCreditCardNumbers(cardNumber2));
console.log(maskCreditCardNumbers(textString));

This approach ensures that the pattern is matched before any replacements are attempted. For instance, in the third test scenario, it outputs an empty string as expected. The regular expression can be modified to accommodate additional credit card number formats beyond those specified in the initial query.

Answer 6

The original poster seems satisfied with the answer provided. I have come up with an alternative solution that utilizes just regular expressions:

function maskNumbers(match, group1, group2, group3) {
  var maskedNums = group2.replace(/\d/g, '*');
  return group1 + " " + maskedNums + " " + group3;
}

function maskCreditCardNumbers(str) {
  var regex = /(\d{4})\s(\d{4}\s\d{4}|\d{6})\s(\d{4}|\d{5})/;

  if (regex.test(str))
    return str.replace(regex, maskNumbers);
  else return "";
}


var cardNumber1 = "4567 6365 7987 3783";
var cardNumber2 = "3457 732837 82372";
var textString = "dfdf dfdf";
console.log(maskCreditCardNumbers(cardNumber1));
console.log(maskCreditCardNumbers(cardNumber2));
console.log(maskCreditCardNumbers(textString));

This approach ensures that the pattern is matched before any replacements are attempted. For instance, in the third test scenario, it outputs an empty string as expected. The regular expression can be modified to accommodate additional credit card number formats beyond those specified in the initial query.

Answer 7

Answer №4

I wanted to provide additional insight on the response given by @Nina Scholz. In the code snippet below, I demonstrate how I utilize the .slice() method to mask a variable under two conditions.

Firstly, we have a simple variable: var n = '12345567890'
Secondly, an array object is used

// Masking a single number
var n = '601115558888';
var singleNumber = n.slice(0, 4) + n.slice(4, n.length -4).replace(/\d/g,'*') + n.slice(n.length -4);
console.log(singleNumber);

// Array of objects
var obj = [{
  contacts_name: 'Jason',
  contacts_num : '651231239991'
},
{
  contacts_name: 'King',
  contacts_num : '60101233321'
}];

// Masking the middle numbers, displaying the first 4 digits and last 4 digits while replacing the rest with *
var num = obj.map((element, index) =>
  element.contacts_num.slice(0,4) 
   + element.contacts_num.slice(4, element.contacts_num.length-4).replace(/\d/g, '*')
   + element.contacts_num.slice(element.contacts_num.length -4)
);

console.log(num);

Answer 8

I wanted to provide additional insight on the response given by @Nina Scholz. In the code snippet below, I demonstrate how I utilize the .slice() method to mask a variable under two conditions.

Firstly, we have a simple variable: var n = '12345567890'
Secondly, an array object is used

// Masking a single number
var n = '601115558888';
var singleNumber = n.slice(0, 4) + n.slice(4, n.length -4).replace(/\d/g,'*') + n.slice(n.length -4);
console.log(singleNumber);

// Array of objects
var obj = [{
  contacts_name: 'Jason',
  contacts_num : '651231239991'
},
{
  contacts_name: 'King',
  contacts_num : '60101233321'
}];

// Masking the middle numbers, displaying the first 4 digits and last 4 digits while replacing the rest with *
var num = obj.map((element, index) =>
  element.contacts_num.slice(0,4) 
   + element.contacts_num.slice(4, element.contacts_num.length-4).replace(/\d/g, '*')
   + element.contacts_num.slice(element.contacts_num.length -4)
);

console.log(num);

Answer 9

Answer №5

If JavaScript is being used for regex masking, the approach is flawed. Ideally, JS should not have access to the original card number except when it is initially received from the user and sent to the server without any masking to allow for typo checks.

Unfortunately, the situation seems quite dire already.

On the server-side, if the card number is already separated by spaces*, one possible solution is: (shown in PHP but adaptable to other languages)

$parts = explode(" ", $fullnumber);
$first = array_shift($parts);
$last = array_pop($parts);
$middle = implode(" ", $parts);
$mask = preg_replace("/\d/", "*", $middle);
$result = "$first $mask $last";

^{* This format is not recommended}

Answer 10

If JavaScript is being used for regex masking, the approach is flawed. Ideally, JS should not have access to the original card number except when it is initially received from the user and sent to the server without any masking to allow for typo checks.

Unfortunately, the situation seems quite dire already.

On the server-side, if the card number is already separated by spaces*, one possible solution is: (shown in PHP but adaptable to other languages)

$parts = explode(" ", $fullnumber);
$first = array_shift($parts);
$last = array_pop($parts);
$middle = implode(" ", $parts);
$mask = preg_replace("/\d/", "*", $middle);
$result = "$first $mask $last";

^{* This format is not recommended}

"Utilize Regular Expressions to conceal part of a text string with a

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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