Sendgrid: Send Bulk Emails

main();
function main(){
  const tempId = configs.get("Template");
  const fromAddress = configs.get("FromAddress");
  const dynamicTemp = engine.findDataByNumber(configs.get("DynamicTemp"));
  const dyTempData = engine.findDataDefinitionByNumber(configs.get("DynamicTemp"));
  const fromName = configs.get("FromName");
  let subData;
  const json = {
    "personalizations": [
      
    ],
    "from": {},
  };
  json["template_id"] = tempId;
  json["from"]["email"] = fromAddress;
  if(fromName !== "" && fromName !== null){
    json["from"]["name"] = fromName;
  }
  if(dynamicTemp === null){
    throw "the table data is empty.";
  }
  const tableSize = dynamicTemp.size();
  const destinationLimit = 200;
  const subdataLimit = 50;
  if(tableSize > destinationLimit){
    throw "number of destination mail addresses can't be over " + destinationLimit + ".";
  }
  if(dynamicTemp.getRow(0).size() > subdataLimit){
      throw "number of subdata can't be over " + subdataLimit + ".";
    }
  for(i=0;i<tableSize;i++){
    json["personalizations"][i] = {
        "to": [{}],
        "dynamic_template_data": {},
      };
    if(dynamicTemp.get(i,0) === "" || dynamicTemp.get(i,0) === null){
      throw "Destination mail address is empty.";
    }
    json["personalizations"][i]["to"][0]["email"] = dynamicTemp.get(i,0);
    if(dynamicTemp.getRow(0).size() > 1){
      if(dynamicTemp.get(i,1) !== "" && dynamicTemp.get(i,1) !== null){
        if(dynamicTemp.get(i,1).search(/[;\,]/) !== -1){
          throw "invalid character is included in the destination name";
        }
        json["personalizations"][i]["to"][0]["name"] = dynamicTemp.get(i,1)
      }
      for(j=2;j<dynamicTemp.getRow(0).size();j++){
        subData = dyTempData.getSubDataDefinitions()[j].getName();
        if(subData !== "" && subData !== null){
          json["personalizations"][i]["dynamic_template_data"][subData] = dynamicTemp.get(i,j);
        }
      }
    }
  }
 const response = httpClient.begin()
    .bearer(configs.get("Key"))
    .body(JSON.stringify(json),"application/json; charset=UTF-8")
    .post("https://api.sendgrid.com/v3/mail/send");

  const status = response.getStatusCode();
  const responseTxt = response.getResponseAsString();
  if (status >= 300) {
    const error = "Failed to send \n status:" + status + "\n" + responseTxt
    throw error;
  }
  engine.log(status);
  engine.log(responseTxt);
}