Today we’re launching the beta version of the new Google Ads scripts experience. Existing scripts won’t be affected, but if you're interested in trying some new features and performance improvements, you can opt in on an individual script basis. To do so, open your script and switch on the new scripts experience (Beta)  toggle above the code:
  Support for ES6, including let, classes, for..of loops, and more. 
  Improved throughput, meaning you can process more entities in the same amount of time. We've also removed the entity limits on processing, although time limits remain in place. 
  More control over setting up and maintaining bidding strategies. 
 
The beta doesn’t currently support manager account scripts or bulk uploads, but watch out for those features in a future update.developers site  for full information on the new experience, including migration information, performance improvements, and updated best practices.forum  so that we can help. - Mike Cloonan, Google Ads Scripts Team