JavaScript IBAN Validator

function normalizeIban(input) {
  return input.replace(/\biban\b/gi, "").replace(/[^a-z0-9]/gi, "").toUpperCase();
}

function mod97(iban) {
  const s = iban.slice(4) + iban.slice(0, 4);
  let r = 0;
  for (const c of s) {
    const v = c >= "A" && c <= "Z" ? String(c.charCodeAt(0) - 55) : c;
    for (const d of v) r = (r * 10 + Number(d)) % 97;
  }
  return r;
}

function isValidIban(input) {
  const iban = normalizeIban(input);
  if (!/^[A-Z]{2}\d{2}[A-Z0-9]+$/.test(iban)) return false;
  return mod97(iban) === 1;
}

console.log(isValidIban("TR14 0001 0050 0123 4567 8901 23")); // true

export function normalizeIban(input: string): string {
  return input.replace(/\biban\b/gi, "").replace(/[^a-z0-9]/gi, "").toUpperCase();
}

export function mod97(iban: string): number {
  const s = iban.slice(4) + iban.slice(0, 4);
  let r = 0;
  for (const c of s) {
    const v = c >= "A" && c <= "Z" ? String(c.charCodeAt(0) - 55) : c;
    for (const d of v) r = (r * 10 + Number(d)) % 97;
  }
  return r;
}

export function isValidIban(input: string): boolean {
  const iban = normalizeIban(input);
  return /^[A-Z]{2}\d{2}[A-Z0-9]+$/.test(iban) && mod97(iban) === 1;
}

import { useMemo, useState } from "react";
import { isValidIban, normalizeIban } from "./iban";

export function useIban(initial = "") {
  const [value, setValue] = useState(initial);
  const valid = useMemo(() => isValidIban(value), [value]);
  return { value, setValue, valid, normalized: normalizeIban(value) };
}

import { z } from "zod";
import { isValidIban } from "./iban";

export const ibanSchema = z
  .string()
  .transform((v) => v.trim())
  .refine(isValidIban, { message: "Geçerli bir IBAN girin." });

<input
  type="text"
  inputmode="text"
  autocomplete="off"
  spellcheck="false"
  pattern="[A-Za-z]{2}[0-9]{2}[A-Za-z0-9 ]{11,34}"
  placeholder="TR14 0001 0050 0123 4567 8901 23"
/>

import { describe, it, expect } from "vitest";
import { isValidIban } from "./iban";

describe("isValidIban", () => {
  it("geçerli TR IBAN", () => {
    expect(isValidIban("TR14 0001 0050 0123 4567 8901 23")).toBe(true);
  });
  it("hatalı kontrol hanesi", () => {
    expect(isValidIban("TR00 0001 0050 0123 4567 8901 23")).toBe(false);
  });
  it("geçerli DE IBAN", () => {
    expect(isValidIban("DE89 3704 0044 0532 0130 00")).toBe(true);
  });
});