Lightning Network short channel id (CLN) to decimal id (LND) converter

scidConverter.ts

/** By LnRouter.app */
function bitShift(n: number, shiftBy: number): number {
    let base = n;
  for (let i = 0; i < shiftBy; i++) {
      base = base * 2;
  }
  return base;
}

/**
 * Takes SCID as input and returns channel ID in decimal,
 * @param {string} scid
 */
export const shortChannelIdToDecimalId = (scid: string): string => {
    const [blockHeightS, transactionIndexS, outputIndexS] = scid.split("x");
    const blockHeight = Number.parseInt(blockHeightS);
    const transactionIndex = Number.parseInt(transactionIndexS);
    const outputIndex = Number.parseInt(outputIndexS);
    const result = BigInt(bitShift(blockHeight, 40)) | BigInt(bitShift(transactionIndex, 16)) | BigInt(outputIndex);
    return result.toString();
}

/**
 * Takes channel id in decimal as input and returns SCID,
 * @param {string} decimalId
 */
 export const channelIdToScid = (decimalId: string): string => {
    // Parse the decimal ID as a BigInt
    const decimalBigInt = BigInt(decimalId);

    // Extract the individual components
    const outputIndex = Number(decimalBigInt & BigInt(0xffff));
    const transactionIndex = Number((decimalBigInt >> BigInt(16)) & BigInt(0xffffff));
    const blockHeight = Number((decimalBigInt >> BigInt(40)) & BigInt(0xffffff));

    // Construct the short channel ID string
    const scid = `${blockHeight}x${transactionIndex}x${outputIndex}`;

    return scid;
  }

const decimalId = shortChannelIdToDecimalId('811818x1325x1');
const channelScid = channelIdToScid('892603330724691969');
console.log(decimalId) // 892603330724691969
console.log(channelScid) // 811818x1325x1