401 error for netsuite REST upsert operation via TBA in node js

I am getting the following error in response while trying to perform the Nestuite upsert operation (https://docs.oracle.com/en/cloud/saas/netsuite/ns-online-help/section_156335203191.html#Using-the-Upsert-Operation) in Node JS :-

Response:

{"type":"https://www.rfc-editor.org/rfc/rfc9110.html#section-15.5.2","title":"Unauthorized","status":401,"o:errorDetails":[{"detail":"Invalid login attempt. For more details, see the Login Audit Trail in the NetSuite UI at Setup > Users/Roles > User Management > View Login Audit Trail.","o:errorCode":"INVALID_LOGIN"}]}

Note: The credentials are correct because it is working perfectly in Postman with TBA and returns 204 response code. Not sure what's going wrong when I try to do the same using Node JS.

Postman screenshot:

Node JS code:

const fetch = require('node-fetch');
const crypto = require('crypto');

function upsertOperation(externalId, body) {

  const baseUrl = `https://${NETSUITE_ACCOUNT_ID}.suitetalk.api.netsuite.com/services/rest/record/v1/${RESOURCE}`;

  const oauthNonce = crypto.randomBytes(32).toString('hex');
  const oauthTimestamp = Math.floor(Date.now() / 1000);
  const oauthSignatureMethod = 'HMAC-SHA256';
  const oauthVersion = '1.0';
  const realm = `${REALM}` // Note: Replaced space with underscore and lower case letters with upper case letters in netsuite account id. Not provided exatct value here.

  const oauthParameters = {
    oauth_consumer_key: CONSUMER_KEY,
    oauth_token: ACCESS_TOKEN,
    oauth_nonce: oauthNonce,
    oauth_timestamp: oauthTimestamp,
    oauth_signature_method: oauthSignatureMethod,
    oauth_version: '1.0'
  };

  const sortedParameters = Object.keys(oauthParameters)
    .sort()
    .map((key) => `${key}=${oauthParameters[key]}`)
    .join('&');

  const signatureBaseString = `PUT&${encodeURIComponent(baseUrl)}&${encodeURIComponent(sortedParameters)}`;
  const signingKey = `${CONSUMER_SECRET}&${ACCESS_TOKEN_SECRET}`;
  const hmac = crypto.createHmac('sha256', signingKey);
  hmac.update(signatureBaseString);
  const oauthSignature = hmac.digest('base64');

  const headers = {
    'Prefer': 'transient',
    'Content-Type': 'application/json',
    'Authorization': `OAuth realm="${realm}",oauth_signature="${oauthSignature}",oauth_nonce="${oauthNonce}",oauth_signature_method="${oauthSignatureMethod}",oauth_consumer_key="${CONSUMER_KEY}",oauth_token="${ACCESS_TOKEN}",oauth_timestamp="${oauthTimestamp}",oauth_version="${oauthVersion}"`
  };

  fetch(baseUrl+'/eid:' + externalId, {
    method: 'PUT',
    headers: headers,
    body: JSON.stringify(body),
    redirect: 'follow'
  })
    .then((response) => response.json())
    .then((data) => {
      console.log('data: ' + JSON.stringify(data));
    })
    .catch((error) => {
      console.error('Error upsertOperation:', error);
    });
}

The entire URL needs to be included in the URI encoding, and the HMAC signing request. However, you're leaving out the '/eid:' + externalId which forms part of the final URL you're accessing. Try it with that included in baseUrl.