minimize-over-delivery.js

//Edit this based on the max amount you want to spend on a given day.
var maxSpend = 1000;

function main () {
  var currentAccount = AdWordsApp.currentAccount();
  var stats = currentAccount.getStatsFor("TODAY");
  var cost = stats.getCost();
  Logger.log("Account has spent " + cost + " so far.");
  if (cost > maxSpend) {
    campaign.pause();
  }
}