Bulk Convert XLSX Files in Google Drive To Google Sheet

code.gs

/*
 * Setttings
 */

// Google Drive Folder ID which contains the Excel files you want to convert
var driveFolderId = '';
// Folder name in which we should place the original files after conversion
var sourceFilesFolderName = 'Source Files';


/*
 * Function convertFiles
 * Converts all xlsx files in the given folder
 */
function convertFiles(){
  if (driveFolderId == '') {
    throw 'Error, driveFolderId is empty';
    return false;
  }
  var excelFiles = DriveApp.getFolderById(driveFolderId).getFilesByType(MimeType.MICROSOFT_EXCEL);
  
  var driveFolderSubFolders = DriveApp.getFolderById(driveFolderId).getFoldersByName(sourceFilesFolderName);
  
  while (driveFolderSubFolders.hasNext()) {
    folder = driveFolderSubFolders.next();
    folderName = folder.getName();

    if (folderName === sourceFilesFolderName) {
      var sourceFilesFolderId = folder.getId();
      break;
    };
  };
  
  if (!sourceFilesFolderId) {
    var sourceFilesFolder = DriveApp.createFolder(sourceFilesFolderName)
    DriveApp.getFolderById(driveFolderId).addFolder(sourceFilesFolder);
    var sourceFilesFolderId = sourceFilesFolder.getId();
  }
  
  while(excelFiles.hasNext()){
    var excelFile = excelFiles.next();
    var name = excelFile.getName();
    var excelFileId = excelFile.getId();
    var excelFileBlob = excelFile.getBlob();
    file = Drive.Files.insert(
      {
        title: name,
        key: excelFileId,
        parents: [{id: driveFolderId}]},
      excelFileBlob,{convert: true}
    );
    // Remove the file from all parent folders
    var parents = excelFile.getParents();
    while (parents.hasNext()) {
      var parent = parents.next();
      parent.removeFile(excelFile);
    }
    // Add the file to the originals folder
    DriveApp.getFolderById(sourceFilesFolderId).addFile(excelFile);
  }
}