This function appends a single row to Google Sheets and repeats itself every 100 milliseconds.

google-api-stresstester.js

const googleapis = require('googleapis');

// Setup:
// (Maybe it's possible to get Client ID, Client Secret, Spreadsheet ID from OAuth Playground? See the link:)
// https://developers.google.com/oauthplayground/
// 
// Otherwise:
// 1. Go to Google Cloud Platform Console > (create a project if needed) > APIs & Services > Library. 
//    Look for "Sheets" and enable the API.
// 2. Go to GCP Console > APIs & Services > OAuth consent screen. EDIT APP and set it to Internal, 
//    and allow the "../auth/drive.file" scope.
// 3. Go to GCP Console > APIs & Services > Credentials. Create new > OAuth client ID > Web application.
// 4. Copy the client ID & client secret, and save them to the environment (CLIENT_ID and CLIENT_SECRET).
// 5. Walk through the OAuth flow  with that client ID and secret, get an auth code. Exchange it for a
//    refresh token. This step requires coding or using cURL to fire at APIs.
// 6. Get a Spreadsheet and Sheet ID from the above stage.
const clientId = process.env.CLIENT_ID;
const clientSecret = process.env.CLIENT_SECRET;
const refreshToken = process.env.REFRESH_TOKEN;
const spreadsheetId = process.env.SPREADSHEET_ID;
const sheetId = process.env.SHEET_ID;

const oauth2Client = new googleapis.google.auth.OAuth2({
  clientId,
  clientSecret,
});


oauth2Client.setCredentials({
  refresh_token: refreshToken,
});

const sheets = googleapis.google.sheets({ version: 'v4' });

let counter = 0;
function makeAppendCellsRequest() {
  counter += 1;
  return {
    appendCells: {
      sheetId,
      rows: [
        {
          values: [
            { userEnteredValue: { stringValue: 'Hello ' + counter } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
            { userEnteredValue: { stringValue: 'World' } },
          ],
        }
      ],
      fields: '*',
    },
  };
}

async function appendRow() {
  console.log('Appending row');
  const result = await sheets.spreadsheets.batchUpdate({
    spreadsheetId,
    auth: oauth2Client,
    resource: {
      requests: [
        makeAppendCellsRequest(),
      ],
    },
  });
  console.log('Appended row, result: ', result);
}

async function loopAppendRows() {
  await appendRow();
  setTimeout(loopAppendRows, 100);
}

loopAppendRows();