How to use the jsrsasign.BigInteger function in jsrsasign

extensions = cert.getInfo().split("X509v3 Extensions:\n")[1].split("signature")[0];

        // Public Key fields
        pkFields.push({
            key: "Algorithm",
            value: pk.type
        });

        if (pk.type === "EC") { // ECDSA
            pkFields.push({
                key: "Curve Name",
                value: pk.curveName
            });
            pkFields.push({
                key: "Length",
                value: (((new r.BigInteger(pk.pubKeyHex, 16)).bitLength()-3) /2) + " bits"
            });
            pkFields.push({
                key: "pub",
                value: PublicKey._formatByteStr(pk.pubKeyHex, 16, 18)
            });
        } else if (pk.type === "DSA") { // DSA
            pkFields.push({
                key: "pub",
                value: PublicKey._formatByteStr(pk.y.toString(16), 16, 18)
            });
            pkFields.push({
                key: "P",
                value: PublicKey._formatByteStr(pk.p.toString(16), 16, 18)
            });
            pkFields.push({
                key: "Q",

if (breakoutSig) { // DSA or ECDSA
            sigStr = "  r:              " + PublicKey._formatByteStr(r.ASN1HEX.getV(sig, 4), 16, 18) + "\n" +
                "  s:              " + PublicKey._formatByteStr(r.ASN1HEX.getV(sig, 48), 16, 18);
        } else { // RSA or unknown
            sigStr = "  Signature:      " + PublicKey._formatByteStr(sig, 16, 18);
        }


        let issuerStr = PublicKey._formatDnStr(issuer, 2),
            nbDate = PublicKey._formatDate(cert.getNotBefore()),
            naDate = PublicKey._formatDate(cert.getNotAfter()),
            subjectStr = PublicKey._formatDnStr(subject, 2);

        return `Version:          ${cert.version} (0x${Utils.hex(cert.version - 1)})
Serial number:    ${new r.BigInteger(sn, 16).toString()} (0x${sn})
Algorithm ID:     ${cert.getSignatureAlgorithmField()}
Validity
  Not Before:     ${nbDate} (dd-mm-yy hh:mm:ss) (${cert.getNotBefore()})
  Not After:      ${naDate} (dd-mm-yy hh:mm:ss) (${cert.getNotAfter()})
Issuer
${issuerStr}
Subject
${subjectStr}
Public Key
${pkStr.slice(0, -1)}
Certificate Signature
  Algorithm:      ${cert.getSignatureAlgorithmName()}
${sigStr}

Extensions
${extensions}`;