From 54f3a07e04e35b00f9e15190736b68e1dc0c61a8 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Thu, 4 Sep 2025 15:29:16 +0200
Subject: [PATCH 1/5] Add string utility function formatSwissIbanNumber

---
 CHANGELOG.md                   |   4 +
 src/lib/string.spec.ts         |  39 +--------
 src/lib/string.ts              | 108 ------------------------
 src/lib/swissStandards.spec.ts |  49 +++++++++++
 src/lib/swissStandards.ts      | 149 +++++++++++++++++++++++++++++++++
 5 files changed, 203 insertions(+), 146 deletions(-)
 create mode 100644 src/lib/swissStandards.spec.ts
 create mode 100644 src/lib/swissStandards.ts

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0a710d1..34ec191 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- `formatSwissIbanNumber` string utility function
+
 ## [2.1.0] - 2025-09-03
 
 ### Added
diff --git a/src/lib/string.spec.ts b/src/lib/string.spec.ts
index 2c0d975..94fc71e 100644
--- a/src/lib/string.spec.ts
+++ b/src/lib/string.spec.ts
@@ -1,12 +1,4 @@
-import {
-  isNullOrEmpty,
-  isNullOrWhitespace,
-  capitalize,
-  uncapitalize,
-  truncate,
-  isValidSwissIbanNumber,
-  isValidSwissSocialSecurityNumber,
-} from "./string";
+import { isNullOrEmpty, isNullOrWhitespace, capitalize, uncapitalize, truncate } from "./string";
 
 describe("string tests", () => {
   test.each([
@@ -128,33 +120,4 @@ describe("string tests", () => {
   ])("truncate without suffix parameter", (value, maxLength, expected) => {
     expect(truncate(value, maxLength)).toBe(expected);
   });
-
-  test.each([
-    [null as unknown as string, false],
-    [undefined as unknown as string, false],
-    ["CH9300762011623852957", true],
-    ["CH93 0076 2011 6238 5295 7", true],
-    ["CH930076 20116238 5295 7", false],
-    ["CH93-0076-2011-6238-5295-7", false],
-    ["CH93 0000 0000 0000 0000 1", false],
-    ["ch93 0076 2011 6238 5295 7", false],
-    ["DE93 0076 2011 6238 5295 7", false],
-  ])("check if this swiss IBAN is valid or not", (unformattedIbanNumber, expected) => {
-    expect(isValidSwissIbanNumber(unformattedIbanNumber)).toBe(expected);
-  });
-
-  test.each([
-    [null as unknown as string, false],
-    [undefined as unknown as string, false],
-    ["7561234567891", false],
-    ["7569217076985", true],
-    ["756.92170769.85", false],
-    ["756.9217.0769.85", true],
-    ["756..9217.0769.85", false],
-    ["756.1234.5678.91", false],
-    ["test756.9217.0769.85", false],
-    ["7.56..9217...0769.85", false],
-  ])("check if the social insurance number is valid or not", (ahvNumber, expected) => {
-    expect(isValidSwissSocialSecurityNumber(ahvNumber)).toBe(expected);
-  });
 });
diff --git a/src/lib/string.ts b/src/lib/string.ts
index c8fbdcb..c0666b3 100644
--- a/src/lib/string.ts
+++ b/src/lib/string.ts
@@ -64,111 +64,3 @@ export function truncate(value: string | undefined, maxLength: number, suffix =
 
   return `${value.slice(0, maxLength)}${suffix}`;
 }
-
-/**
- * Checks if the provided string is a valid swiss IBAN number
- * @param ibanNumber The provided IBAN number to check
- * Must be in one of the following formats:
- * - "CHXX XXXX XXXX XXXX XXXX X" with whitespaces
- * - "CHXXXXXXXXXXXXXXXXXXX" without whitespaces
- * @returns The result of the IBAN number check
- */
-export function isValidSwissIbanNumber(ibanNumber: string): boolean {
-  // 1. Reject null, undefined or whitespace-only strings
-  if (isNullOrWhitespace(ibanNumber)) {
-    return false;
-  }
-
-  // 2. Define allowed strict formats
-  //    - with spaces: "CHXX XXXX XXXX XXXX XXXX X"
-  const compactIbanNumberWithWhiteSpaces = new RegExp(/^CH\d{2}(?: \d{4}){4} \d{1}$/);
-  //    - without spaces: "CHXXXXXXXXXXXXXXXXXXX"
-  const compactIbanNumberWithoutWhiteSpaces = new RegExp(/^CH\d{19}$/);
-
-  // 3. Check if input matches one of the allowed formats
-  if (!compactIbanNumberWithWhiteSpaces.test(ibanNumber) && !compactIbanNumberWithoutWhiteSpaces.test(ibanNumber)) {
-    return false;
-  }
-
-  // 4. Remove all spaces to get a compact IBAN string
-  const compactIbanNumber = ibanNumber.replaceAll(" ", "");
-
-  // 5. Rearrange IBAN for checksum calculation
-  //    - move first 4 characters (CH + 2 check digits) to the end
-  const rearrangedIban = compactIbanNumber.slice(4) + compactIbanNumber.slice(0, 4);
-
-  // 6. Replace letters with numbers (A=10, B=11, ..., Z=35)
-  const numericStr = rearrangedIban.replaceAll(/[A-Z]/g, (ch) => (ch.codePointAt(0)! - 55).toString());
-
-  // 7. Perform modulo 97 calculation to validate IBAN
-  let restOfCalculation = 0;
-  for (const digit of numericStr) {
-    restOfCalculation = (restOfCalculation * 10 + Number(digit)) % 97;
-  }
-
-  // 8. IBAN is valid only if the remainder equals 1
-  return restOfCalculation === 1;
-}
-
-/**
- * Validation of social insurance number with checking the checksum
- * Validation according to https://www.sozialversicherungsnummer.ch/aufbau-neu.htm
- * @param socialInsuranceNumber The social insurance number to check
- * Must be in one of the following formats:
- * - "756.XXXX.XXXX.XX" with dots as separators
- * - "756XXXXXXXXXX" with digits only
- * @returns The result if the social insurance number is valid or not
- */
-export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string): boolean {
-  // 1. Check if input is empty or only whitespace
-  if (isNullOrWhitespace(socialInsuranceNumber)) {
-    return false;
-  }
-
-  /**
-   * 2. Check if input matches accepted formats:
-   *    - With dots: 756.XXXX.XXXX.XX
-   *    - Without dots: 756XXXXXXXXXX
-   */
-  const socialInsuranceNumberWithDots = new RegExp(/^756\.\d{4}\.\d{4}\.\d{2}$/);
-  const socialInsuranceNumberWithoutDots = new RegExp(/^756\d{10}$/);
-
-  if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber) && !socialInsuranceNumberWithoutDots.test(socialInsuranceNumber)) {
-    return false;
-  }
-
-  // 3. Remove all dots → get a string of 13 digits
-  const compactNumber = socialInsuranceNumber.replaceAll(".", "");
-
-  /**
-   * 4. Separate digits for checksum calculation
-   *    - first 12 digits: used to calculate checksum
-   *    - last digit: actual check digit
-   */
-  const digits = compactNumber.slice(0, -1);
-  const reversedDigits = [...digits].reverse().join("");
-  const reversedDigitsArray = [...reversedDigits];
-
-  /*
-   * 5. Calculate weighted sum for checksum
-   *    - Even positions (after reversing) ×3
-   *    - Odd positions ×1
-   */
-  let sum = 0;
-  for (const [i, element] of reversedDigitsArray.entries()) {
-    sum += i % 2 === 0 ? Number(element) * 3 : Number(element) * 1;
-  }
-
-  /*
-   * 6. Calculate expected check digit
-   *    - Check digit = value to reach next multiple of 10
-   */
-  const checksum = (10 - (sum % 10)) % 10;
-  const checknumber = Number.parseInt(compactNumber.slice(-1));
-
-  /*
-   * 7. Compare calculated check digit with actual last digit
-   *    - If equal → valid AHV number
-   */
-  return checksum === checknumber;
-}
diff --git a/src/lib/swissStandards.spec.ts b/src/lib/swissStandards.spec.ts
new file mode 100644
index 0000000..3ef87ec
--- /dev/null
+++ b/src/lib/swissStandards.spec.ts
@@ -0,0 +1,49 @@
+import { isValidSwissIbanNumber, isValidSwissSocialSecurityNumber, formatSwissIbanNumber } from "./swissStandards";
+
+describe("Swiss standards test", () => {
+  test.each([
+    [null as unknown as string, false],
+    [undefined as unknown as string, false],
+    ["CH9300762011623852957", true],
+    ["CH93 0076 2011 6238 5295 7", true],
+    ["CH930076 20116238 5295 7", false],
+    ["CH93-0076-2011-6238-5295-7", false],
+    ["CH93 0000 0000 0000 0000 1", false],
+    ["ch93 0076 2011 6238 5295 7", false],
+    ["c93 0076 2011 6238 5295 7", false],
+    ["DE93 0076 2011 6238 5295 7", false],
+  ])("check if this swiss IBAN is valid or not", (unformattedIbanNumber, expected) => {
+    expect(isValidSwissIbanNumber(unformattedIbanNumber)).toBe(expected);
+  });
+
+  test.each([
+    [null as unknown as string, false],
+    [undefined as unknown as string, false],
+    ["7561234567891", false],
+    ["7569217076985", true],
+    ["756.92170769.85", false],
+    ["756.9217.0769.85", true],
+    ["756..9217.0769.85", false],
+    ["756.1234.5678.91", false],
+    ["test756.9217.0769.85", false],
+    ["7.56..9217...0769.85", false],
+  ])("check if the social insurance number is valid or not", (ahvNumber, expected) => {
+    expect(isValidSwissSocialSecurityNumber(ahvNumber)).toBe(expected);
+  });
+
+  test.each([
+    [null as unknown as string, null, false],
+    [undefined as unknown as string, undefined, false],
+    ["CH9300762011623852957", "CH93 0076 2011 6238 5295 7", true],
+    ["ch9300762011623852957", "CH93 0076 2011 6238 5295 7", true],
+    ["ch9301234567891011127", "CH93 0123 4567 8910 1112 7", false],
+    ["DE93 00 76 2011 62385295 7", "DE93 00 76 2011 62385295 7", false],
+    ["D 93 00 76 2011 62385295 7", "D 93 00 76 2011 62385295 7", false],
+    ["Ch 93 0076 20 1 162385 295 7", "CH93 0076 2011 6238 5295 7", true],
+  ])("Check if the IBAN number gets formatted correctly", (unformattedIbanNumber, expectedIbanNumber, expectedIsValid) => {
+    const result = formatSwissIbanNumber(unformattedIbanNumber);
+
+    expect(result.ibanNumber).toBe(expectedIbanNumber);
+    expect(result.isValidSwissIbanNumber).toBe(expectedIsValid);
+  });
+});
diff --git a/src/lib/swissStandards.ts b/src/lib/swissStandards.ts
new file mode 100644
index 0000000..4c3586f
--- /dev/null
+++ b/src/lib/swissStandards.ts
@@ -0,0 +1,149 @@
+import { isNullOrWhitespace } from "./string";
+
+/**
+ * Checks if the provided string is a valid swiss IBAN number
+ * @param ibanNumber The provided IBAN number to check
+ * Must be in one of the following formats:
+ * - "CHXX XXXX XXXX XXXX XXXX X" with whitespaces
+ * - "CHXXXXXXXXXXXXXXXXXXX" without whitespaces
+ * @returns The result of the IBAN number check
+ */
+export function isValidSwissIbanNumber(ibanNumber: string): boolean {
+  // 1. Reject null, undefined or whitespace-only strings
+  if (isNullOrWhitespace(ibanNumber)) {
+    return false;
+  }
+
+  // 2. Define allowed strict formats
+  //    - with spaces: "CHXX XXXX XXXX XXXX XXXX X"
+  const compactIbanNumberWithWhiteSpaces = new RegExp(/^CH\d{2}(?: \d{4}){4} \d{1}$/);
+  //    - without spaces: "CHXXXXXXXXXXXXXXXXXXX"
+  const compactIbanNumberWithoutWhiteSpaces = new RegExp(/^CH\d{19}$/);
+
+  // 3. Check if input matches one of the allowed formats
+  if (!compactIbanNumberWithWhiteSpaces.test(ibanNumber) && !compactIbanNumberWithoutWhiteSpaces.test(ibanNumber)) {
+    return false;
+  }
+
+  // 4. Remove all spaces to get a compact IBAN string
+  const compactIbanNumber = ibanNumber.replaceAll(" ", "");
+
+  // 5. Rearrange IBAN for checksum calculation
+  //    - move first 4 characters (CH + 2 check digits) to the end
+  const rearrangedIban = compactIbanNumber.slice(4) + compactIbanNumber.slice(0, 4);
+
+  // 6. Replace letters with numbers (A=10, B=11, ..., Z=35)
+  const numericStr = rearrangedIban.replaceAll(/[A-Z]/g, (ch) => (ch.codePointAt(0)! - 55).toString());
+
+  // 7. Perform modulo 97 calculation to validate IBAN
+  let restOfCalculation = 0;
+  for (const digit of numericStr) {
+    restOfCalculation = (restOfCalculation * 10 + Number(digit)) % 97;
+  }
+
+  // 8. IBAN is valid only if the remainder equals 1
+  return restOfCalculation === 1;
+}
+
+/**
+ * Validation of social insurance number with checking the checksum
+ * Validation according to https://www.sozialversicherungsnummer.ch/aufbau-neu.htm
+ * @param socialInsuranceNumber The social insurance number to check
+ * Must be in one of the following formats:
+ * - "756.XXXX.XXXX.XX" with dots as separators
+ * - "756XXXXXXXXXX" with digits only
+ * @returns The result if the social insurance number is valid or not
+ */
+export function isValidSwissSocialSecurityNumber(socialInsuranceNumber: string): boolean {
+  // 1. Check if input is empty or only whitespace
+  if (isNullOrWhitespace(socialInsuranceNumber)) {
+    return false;
+  }
+
+  /**
+   * 2. Check if input matches accepted formats:
+   *    - With dots: 756.XXXX.XXXX.XX
+   *    - Without dots: 756XXXXXXXXXX
+   */
+  const socialInsuranceNumberWithDots = new RegExp(/^756\.\d{4}\.\d{4}\.\d{2}$/);
+  const socialInsuranceNumberWithoutDots = new RegExp(/^756\d{10}$/);
+
+  if (!socialInsuranceNumberWithDots.test(socialInsuranceNumber) && !socialInsuranceNumberWithoutDots.test(socialInsuranceNumber)) {
+    return false;
+  }
+
+  // 3. Remove all dots → get a string of 13 digits
+  const compactNumber = socialInsuranceNumber.replaceAll(".", "");
+
+  /**
+   * 4. Separate digits for checksum calculation
+   *    - first 12 digits: used to calculate checksum
+   *    - last digit: actual check digit
+   */
+  const digits = compactNumber.slice(0, -1);
+  const reversedDigits = [...digits].reverse().join("");
+  const reversedDigitsArray = [...reversedDigits];
+
+  /*
+   * 5. Calculate weighted sum for checksum
+   *    - Even positions (after reversing) ×3
+   *    - Odd positions ×1
+   */
+  let sum = 0;
+  for (const [i, element] of reversedDigitsArray.entries()) {
+    sum += i % 2 === 0 ? Number(element) * 3 : Number(element) * 1;
+  }
+
+  /*
+   * 6. Calculate expected check digit
+   *    - Check digit = value to reach next multiple of 10
+   */
+  const checksum = (10 - (sum % 10)) % 10;
+  const checknumber = Number.parseInt(compactNumber.slice(-1));
+
+  /*
+   * 7. Compare calculated check digit with actual last digit
+   *    - If equal → valid AHV number
+   */
+  return checksum === checknumber;
+}
+
+/**
+ * Formats a Swiss IBAN number to the standard of "CHXX XXXX XXXX XXXX XXXX X"
+ * @param unformattedIbanNumber the IBAN number to format
+ * @returns a object containing the formatted IBAN number and a boolean indicating if the IBAN number was valid or not
+ */
+export function formatSwissIbanNumber(unformattedIbanNumber: string): {
+  /**
+   * The formatted IBAN number or the original input if the unformatted IBAN number was invalid
+   */
+  ibanNumber: string;
+  /**
+   * The result if the IBAN number is valid or not
+   */
+  isValidSwissIbanNumber: boolean;
+} {
+  // 1. Check if the unformatted IBAN number is empty or only a whitespace
+  if (isNullOrWhitespace(unformattedIbanNumber)) {
+    return { ibanNumber: unformattedIbanNumber, isValidSwissIbanNumber: false };
+  }
+
+  // 2. Remove all non-alphanumeric characters and convert letters to uppercase
+  const cleanedIbanNumber = unformattedIbanNumber.replaceAll(/[^A-Z0-9]/gi, "").toUpperCase();
+
+  // 3. Check if it is possible to format a new IBAN number
+  if (!/^CH\d{19}$/.test(cleanedIbanNumber)) {
+    return { ibanNumber: unformattedIbanNumber, isValidSwissIbanNumber: false };
+  }
+
+  // 4. Format the cleaned IBAN number into groups of 4 characters separated by spaces
+  const formattedIbanNumber = cleanedIbanNumber.replaceAll(/(.{4})/g, "$1 ").trim();
+
+  // 5. If the Swiss IBAN number is valid return the formatted IBAN number with the true status
+  if (isValidSwissIbanNumber(formattedIbanNumber)) {
+    return { ibanNumber: formattedIbanNumber, isValidSwissIbanNumber: true };
+  }
+
+  // 6. If the Swiss IBAN number is not valid return the formatted IBAN number with the false status
+  return { ibanNumber: formattedIbanNumber, isValidSwissIbanNumber: false };
+}

From 9a01b0873ebd91adfabb714c4aa62c2ff8257d05 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Mon, 8 Sep 2025 10:40:11 +0200
Subject: [PATCH 2/5] Formatted

---
 src/lib/swissStandards.spec.ts | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/lib/swissStandards.spec.ts b/src/lib/swissStandards.spec.ts
index 61c31c6..202486f 100644
--- a/src/lib/swissStandards.spec.ts
+++ b/src/lib/swissStandards.spec.ts
@@ -27,8 +27,8 @@ describe("Swiss standards test", () => {
     ["756.1234.5678.91", false],
     ["test756.9217.0769.85", false],
     ["7.56..9217...0769.85", false],
-  ])("check if the social insurance number is valid or not", (ahvNumber, expected) => {
-    expect(isValidSwissSocialInsuranceNumber(ahvNumber)).toBe(expected);
+  ])("check if the social insurance number is valid or not", (swissSocialInsuranceNumber, expected) => {
+    expect(isValidSwissSocialInsuranceNumber(swissSocialInsuranceNumber)).toBe(expected);
   });
 
   test.each([
@@ -45,6 +45,5 @@ describe("Swiss standards test", () => {
 
     expect(result.ibanNumber).toBe(expectedIbanNumber);
     expect(result.isValidSwissIbanNumber).toBe(expectedIsValid);
-    expect(isValidSwissSocialInsuranceNumber(ahvNumber)).toBe(expected);
   });
 });

From 32c538abff91aa996e8337eedc457348f08edcfa Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Mon, 8 Sep 2025 16:40:06 +0200
Subject: [PATCH 3/5] Fixed changelog

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ad61e04..918b338 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,7 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- `formatSwissIbanNumber` string utility function
+- `formatSwissIbanNumber` swiss standard function
 
 ### Changed
 

From fe089caca11c7de7f4cf1e2b5d49a8fc9052430f Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Wed, 1 Oct 2025 16:06:33 +0200
Subject: [PATCH 4/5] Added Swiss standards function tryParseSwissIbanNumber

---
 CHANGELOG.md                   |  2 +-
 src/lib/swissStandards.spec.ts | 58 ++++++++++++++++++++++++----------
 src/lib/swissStandards.ts      | 47 +++++++++------------------
 3 files changed, 58 insertions(+), 49 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7aa71cc..3a0517b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,7 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - `splitLines` string utility function
-- `formatSwissIbanNumber` swiss standard function
+- `tryParseSwissIbanNumber` swiss standard function
 - `trimStart`, `trimEnd` and `trim` string type utility functions
 
 ### Changed
diff --git a/src/lib/swissStandards.spec.ts b/src/lib/swissStandards.spec.ts
index 4444a2b..2174416 100644
--- a/src/lib/swissStandards.spec.ts
+++ b/src/lib/swissStandards.spec.ts
@@ -1,4 +1,4 @@
-import { isValidSwissIbanNumber, isValidSwissSocialInsuranceNumber, formatSwissIbanNumber } from "./swissStandards";
+import { isValidSwissIbanNumber, isValidSwissSocialInsuranceNumber, tryParseSwissIbanNumber } from "./swissStandards";
 
 describe("Swiss standards test", () => {
   test.each([
@@ -12,7 +12,7 @@ describe("Swiss standards test", () => {
     ["ch93 0076 2011 6238 5295 7", false],
     ["c93 0076 2011 6238 5295 7", false],
     ["DE93 0076 2011 6238 5295 7", false],
-  ])("check if the swiss IBAN number is valid or not", (iBanNumberToCheck, expected) => {
+  ])("check if the Swiss IBAN number is valid or not", (iBanNumberToCheck, expected) => {
     expect(isValidSwissIbanNumber(iBanNumberToCheck)).toBe(expected);
   });
 
@@ -25,7 +25,7 @@ describe("Swiss standards test", () => {
     ["DE34 0076 2ABC 123D EF45 3", false],
     ["CH34 0076 2ABC 123D EF45 \n6", false],
     ["CH34 0076 2ABC 123D EF45 !", false],
-  ])("check if the siwss IBAN number with letters is valid or not", (iBanNumberToCheck, expected) => {
+  ])("check if the Swiss IBAN number with letters is valid or not", (iBanNumberToCheck, expected) => {
     expect(isValidSwissIbanNumber(iBanNumberToCheck)).toBe(expected);
   });
 
@@ -45,18 +45,44 @@ describe("Swiss standards test", () => {
   });
 
   test.each([
-    [null as unknown as string, null, false],
-    [undefined as unknown as string, undefined, false],
-    ["CH9300762011623852957", "CH93 0076 2011 6238 5295 7", true],
-    ["ch9300762011623852957", "CH93 0076 2011 6238 5295 7", true],
-    ["ch9301234567891011127", "CH93 0123 4567 8910 1112 7", false],
-    ["DE93 00 76 2011 62385295 7", "DE93 00 76 2011 62385295 7", false],
-    ["D 93 00 76 2011 62385295 7", "D 93 00 76 2011 62385295 7", false],
-    ["Ch 93 0076 20 1 162385 295 7", "CH93 0076 2011 6238 5295 7", true],
-  ])("Check if the IBAN number gets formatted correctly", (unformattedIbanNumber, expectedIbanNumber, expectedIsValid) => {
-    const result = formatSwissIbanNumber(unformattedIbanNumber);
-
-    expect(result.ibanNumber).toBe(expectedIbanNumber);
-    expect(result.isValidSwissIbanNumber).toBe(expectedIsValid);
+    [null as unknown as string, { isValid: false, iban: undefined, ibanFormatted: undefined }],
+    [undefined as unknown as string, { isValid: false, iban: undefined, ibanFormatted: undefined }],
+    ["", { isValid: false, iban: undefined, ibanFormatted: undefined }],
+    ["CH94 0076 2011 6238 5295 7", { isValid: false, iban: undefined, ibanFormatted: undefined }],
+    ["CH1000000ABC123DEF456", { isValid: false, iban: undefined, ibanFormatted: undefined }],
+    [
+      "CH9300762011623852957",
+      {
+        isValid: true,
+        iban: "CH9300762011623852957",
+        ibanFormatted: "CH93 0076 2011 6238 5295 7",
+      },
+    ],
+    [
+      "CH3400762ABC123DEF456",
+      {
+        isValid: true,
+        iban: "CH3400762ABC123DEF456",
+        ibanFormatted: "CH34 0076 2ABC 123D EF45 6",
+      },
+    ],
+    [
+      "CH93 0076 2011 6238 5295 7",
+      {
+        isValid: true,
+        iban: "CH9300762011623852957",
+        ibanFormatted: "CH93 0076 2011 6238 5295 7",
+      },
+    ],
+    [
+      "CH34 0076 2ABC 123D EF45 6",
+      {
+        isValid: true,
+        iban: "CH3400762ABC123DEF456",
+        ibanFormatted: "CH34 0076 2ABC 123D EF45 6",
+      },
+    ],
+  ])("check if the Swiss IBAN number gets parsed correctly", (unformattedSwissIbanNumber, expected) => {
+    expect(tryParseSwissIbanNumber(unformattedSwissIbanNumber)).toEqual(expected);
   });
 });
diff --git a/src/lib/swissStandards.ts b/src/lib/swissStandards.ts
index 3d05ae3..ac13650 100644
--- a/src/lib/swissStandards.ts
+++ b/src/lib/swissStandards.ts
@@ -109,41 +109,24 @@ export function isValidSwissSocialInsuranceNumber(socialInsuranceNumber: string)
 }
 
 /**
- * Formats a Swiss IBAN number to the standard of "CHXX XXXX XXXX XXXX XXXX X"
- * @param unformattedIbanNumber the IBAN number to format
- * @returns a object containing the formatted IBAN number and a boolean indicating if the IBAN number was valid or not
+ * Attempts to parse and validate a Swiss IBAN.
+ * @param unformattedIbanNumber - The unformatted IBAN as a string
+ * @returns The result object with the following properties:
+ * @property {boolean} isValid - Indicates whether the IBAN is valid or not
+ * @property {string} iban - The cleaned IBAN, only present if valid
+ * @property {string} ibanFormatted - The formatted IBAN, only present if valid
  */
-export function formatSwissIbanNumber(unformattedIbanNumber: string): {
-  /**
-   * The formatted IBAN number or the original input if the unformatted IBAN number was invalid
-   */
-  ibanNumber: string;
-  /**
-   * The result if the IBAN number is valid or not
-   */
-  isValidSwissIbanNumber: boolean;
-} {
-  // 1. Check if the unformatted IBAN number is empty or only a whitespace
+export function tryParseSwissIbanNumber(unformattedIbanNumber?: string) {
   if (isNullOrWhitespace(unformattedIbanNumber)) {
-    return { ibanNumber: unformattedIbanNumber, isValidSwissIbanNumber: false };
+    return { isValid: false };
   }
 
-  // 2. Remove all non-alphanumeric characters and convert letters to uppercase
-  const cleanedIbanNumber = unformattedIbanNumber.replaceAll(/[^A-Z0-9]/gi, "").toUpperCase();
-
-  // 3. Check if it is possible to format a new IBAN number
-  if (!/^CH\d{19}$/.test(cleanedIbanNumber)) {
-    return { ibanNumber: unformattedIbanNumber, isValidSwissIbanNumber: false };
-  }
-
-  // 4. Format the cleaned IBAN number into groups of 4 characters separated by spaces
-  const formattedIbanNumber = cleanedIbanNumber.replaceAll(/(.{4})/g, "$1 ").trim();
-
-  // 5. If the Swiss IBAN number is valid return the formatted IBAN number with the true status
-  if (isValidSwissIbanNumber(formattedIbanNumber)) {
-    return { ibanNumber: formattedIbanNumber, isValidSwissIbanNumber: true };
-  }
+  const iban = unformattedIbanNumber!.replaceAll(/[^A-Z0-9]/gi, "").toUpperCase();
+  const isValid = isValidSwissIbanNumber(iban);
 
-  // 6. If the Swiss IBAN number is not valid return the formatted IBAN number with the false status
-  return { ibanNumber: formattedIbanNumber, isValidSwissIbanNumber: false };
+  return {
+    isValid: isValid,
+    iban: isValid ? iban : undefined,
+    ibanFormatted: isValid ? iban.match(/.{1,4}/g)?.join(" ") : undefined,
+  };
 }

From 44bd2af8187de2b326894956a3011062310a08b1 Mon Sep 17 00:00:00 2001
From: Dominic Baur <dominic.baur@collana.com>
Date: Wed, 1 Oct 2025 16:24:33 +0200
Subject: [PATCH 5/5] Added another testcase

---
 src/lib/swissStandards.spec.ts | 37 +++++-----------------------------
 1 file changed, 5 insertions(+), 32 deletions(-)

diff --git a/src/lib/swissStandards.spec.ts b/src/lib/swissStandards.spec.ts
index 2174416..9708e93 100644
--- a/src/lib/swissStandards.spec.ts
+++ b/src/lib/swissStandards.spec.ts
@@ -50,38 +50,11 @@ describe("Swiss standards test", () => {
     ["", { isValid: false, iban: undefined, ibanFormatted: undefined }],
     ["CH94 0076 2011 6238 5295 7", { isValid: false, iban: undefined, ibanFormatted: undefined }],
     ["CH1000000ABC123DEF456", { isValid: false, iban: undefined, ibanFormatted: undefined }],
-    [
-      "CH9300762011623852957",
-      {
-        isValid: true,
-        iban: "CH9300762011623852957",
-        ibanFormatted: "CH93 0076 2011 6238 5295 7",
-      },
-    ],
-    [
-      "CH3400762ABC123DEF456",
-      {
-        isValid: true,
-        iban: "CH3400762ABC123DEF456",
-        ibanFormatted: "CH34 0076 2ABC 123D EF45 6",
-      },
-    ],
-    [
-      "CH93 0076 2011 6238 5295 7",
-      {
-        isValid: true,
-        iban: "CH9300762011623852957",
-        ibanFormatted: "CH93 0076 2011 6238 5295 7",
-      },
-    ],
-    [
-      "CH34 0076 2ABC 123D EF45 6",
-      {
-        isValid: true,
-        iban: "CH3400762ABC123DEF456",
-        ibanFormatted: "CH34 0076 2ABC 123D EF45 6",
-      },
-    ],
+    ["CH93-0076,2011.6238\n5295\n7", { isValid: true, iban: "CH9300762011623852957", ibanFormatted: "CH93 0076 2011 6238 5295 7" }],
+    ["CH9300762011623852957", { isValid: true, iban: "CH9300762011623852957", ibanFormatted: "CH93 0076 2011 6238 5295 7" }],
+    ["CH3400762ABC123DEF456", { isValid: true, iban: "CH3400762ABC123DEF456", ibanFormatted: "CH34 0076 2ABC 123D EF45 6" }],
+    ["CH93 0076 2011 6238 5295 7", { isValid: true, iban: "CH9300762011623852957", ibanFormatted: "CH93 0076 2011 6238 5295 7" }],
+    ["CH34 0076 2ABC 123D EF45 6", { isValid: true, iban: "CH3400762ABC123DEF456", ibanFormatted: "CH34 0076 2ABC 123D EF45 6" }],
   ])("check if the Swiss IBAN number gets parsed correctly", (unformattedSwissIbanNumber, expected) => {
     expect(tryParseSwissIbanNumber(unformattedSwissIbanNumber)).toEqual(expected);
   });