Get content of user-attributed revision to a Google Sheet

getUserRevision.js

/*
 * Seth Battis
 * Google Apps Script
 * No external dependencies
 */

/**
 * @param fileId: string - Google Sheets document ID
 * @param tileIndex: number - index of "combined revisions" shown in versions UI
 */
function test(fileId, tileIndex) {
  const tiles = getRevisionTiles(fileId)
  Logger.log(`Revision "Tile" ${tileIndex}, Changes by ${tiles.tileInfo[tileIndex].users.map(id => tiles.userMap[id].name).join(', ')}`)
  Logger.log(getRevisionComparision(fileId, tiles.tileInfo[tileIndex].end, tiles.tileInfo[tileIndex].start))
}

function getRevisionTiles(fileId) {
    return JSON.parse(UrlFetchApp.fetch(`https://docs.google.com/spreadsheets/d/${fileId}/revisions/tiles?id=${fileId}&start=1&revisionBatchSize=1500&showDetailedRevisions=false&loadType=0&includes_info_params=true&cros_files=false`, {
      headers: {
        Authorization: `Bearer ${ScriptApp.getOAuthToken()}`
      }
    }).getContentText().substring(4))
}

function getRevisionComparision(fileId, revisionId, previousRevisionId) {
  return UrlFetchApp.fetch(`https://docs.google.com/spreadsheets/d/${fileId}/revisions/show?includes_info_params=true&cros_files=false&rev=${revisionId}&fromRev=${previousRevisionId}`, {
    headers: {
      Authorization: `Bearer ${ScriptApp.getOAuthToken()}`
    }
  })
}