Label to delete gMail threads matching a search query - Apps Script

Code.gs

/**
 * @fileoverview Utility to delete old threads from a search.
 * This is an Apps Script code.
 *
 * Example of usage:
 * Go to scripts.google.com and click 'New script'.
 * Enable V8, as the code is written with ES6 features.
 * Change QUERY_SEARCH to a gMail search/filter that matches
 * the emails you want to delete. For example:
 * 'label:coding older_than:1m'
 * matches threads in coding label older than a month.
 * Run 'deleteMatchingThreadsDryRun' to make sure it matches
 * the desired threads by checking the logs.
 * When confirmed, set a new recurrent trigger:
 * Edit > Current project's triggers > Add trigger.
 * Choose which function to run: 'deleteMatchingThreads'.
 * Select type of time based trigger: hour/day/week/month
 * depending on what frequency suits you.
 * Click 'Save'.
 */

// Change for the search query that you want to delete.
const QUERY_SEARCH = 'label:coding older_than:1m';

/**
 * Runs deleting functions without deleting threads.
 * Logs messages on the number and subjects of the threads
 * that would have been deleted if run.
 */
function deleteMatchingThreadsDryRun() {
  _deleteMatchingThreads(/* dryRun = */ true);
}

/**
 * Runs deleting functions without deleting threads.
 * Logs messages on the number and subjects of the threads
 * that would have been deleted if run.
 */
function deleteMatchingThreads() {
  _deleteMatchingThreads(/* dryRun = */ false);
}

/**
 * Deletes threads matching QUERY_SEARCH rules.
 * @param {boolean=} dryRun Whether run should actually delete messages.
 *    If true, it won't delete it. By default, this is true. 
 */
function _deleteMatchingThreads(dryRun = true) {
  Logger.log('Received request to delete emails matching: ' + QUERY_SEARCH);
  Logger.log('Dry run? ' + dryRun);
  const matchingThreads = GmailApp.search(QUERY_SEARCH);
  Logger.log('Found ' + matchingThreads.length + ' matching threads.');
  for(const thread of matchingThreads) {
    if (dryRun === false) thread.moveToTrash();
    Logger.log('Deleting thread: ' + thread.getFirstMessageSubject());
  }
}