Validate a credit card number (#1430)

* Script.js

* readme.md

Author: himanshu7895

Catalog Client Script/Validate a Credit Card Number/Script.js

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+function onSubmit() {
+    var cardNumber = g_form.getValue('credit_card'); // Change 'credit_card' to your field name
+    var cardPattern = /^\d{16}$/; // Simple pattern for 16-digit cards
+
+    if (!cardPattern.test(cardNumber) || !isValidCardNumber(cardNumber)) {
+        g_form.showFieldMsg('credit_card', 'Please enter a valid 16-digit credit card number.', 'error');
+        return false;
+    }
+    return true;
+}
+
+function isValidCardNumber(number) {
+    var sum = 0;
+    var alternate = false;
+    for (var i = number.length - 1; i >= 0; i--) {
+        var n = parseInt(number.charAt(i), 10);
+        if (alternate) {
+            n *= 2;
+            if (n > 9) n -= 9;
+        }
+        sum += n;
+        alternate = !alternate;
+    }
+    return sum % 10 === 0;
+}

Catalog Client Script/Validate a Credit Card Number/readme.md

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+**Description of the Credit Card Number Validation Script**
+Purpose
+The script validates a credit card number entered by the user in a ServiceNow form. 
+It checks if the number is a valid 16-digit credit card number using a combination of a regular expression and the Luhn algorithm for basic validation.
+
+**Validation Criteria**
+Format:
+The credit card number must consist of exactly 16 digits.
+**Luhn Algorithm:**
+The script implements the Luhn algorithm to determine if the credit card number is potentially valid. 
+This algorithm helps catch common errors in credit card numbers, such as transposed digits.