QRIS (Quick Response Code Indonesian Standard). Convert Static QRIS to QRIS with nominal information.

qrisConverter.ts

export interface QrisSettings {
  /** Payment amount (as string number) */
  nominal: string;
  /** Service fee type: 'p' for percentage, 'r' for fixed value (rupiah) */
  feeType?: "p" | "r";
  /** Service fee value (as string number) */
  feeValue?: string;
}

function padLength(length: number): string {
  return length < 10 ? "0" + length : length.toString();
}

/**
 * Calculates CRC16 (Cyclic Redundancy Check) from input string
 * CRC16 is a 16-bit error-detecting code used to verify data integrity
 */
function calculateCRC16(input: string): string {
  let crc = 0xffff;

  for (let i = 0; i < input.length; i++) {
    crc ^= input.charCodeAt(i) << 8;

    for (let j = 0; j < 8; j++) {
      crc = crc & 0x8000 ? (crc << 1) ^ 0x1021 : crc << 1;
    }
  }

  const hex = (crc & 0xffff).toString(16).toUpperCase();

  return hex.padStart(4, "0");
}

function convertToDynamicQRIS(
  staticQris: string,
  settings: QrisSettings,
): string {
  const { nominal, feeType = "p", feeValue = "0" } = settings;

  const qris = staticQris.slice(0, -4).replace("010211", "010212");

  const [prefix, suffix] = qris.split("5802ID");
  const amountData = "54" + padLength(nominal.length) + nominal;

  let feeData = "";
  if (feeValue && feeValue !== "0") {
    feeData =
      feeType === "p"
        ? "55020357" + padLength(feeValue.length) + feeValue
        : "55020256" + padLength(feeValue.length) + feeValue;
  }

  const resultQRIS = `${prefix}${amountData}${feeData}5802ID${suffix}`;
  return resultQRIS + calculateCRC16(resultQRIS);
}

export { convertToDynamicQRIS };