sample1.js

function myFunction() {
  
  var response = UrlFetchApp.fetch("https://so2-api.mutoys.com/json/sale/all.json");
  
  var json = JSON.parse(response.getContentText());
  
  var n = 0;
  while(1){
    try{
      var st = json[n]["item_id"];
      var dat = st + "," + n;
      Logger.log(dat);
      n++;
    }
    catch(e){
      break;
    }
  }
}