mikeal/request is used for fetching web pages so any desired option from this package can be passed to Krawler's constructor. After Krawler emits the 'data' event, it automatically continues to a next url address. It does not care if the result was processed or not. If you would like to have a full control over the result handling, you can turn on the custom callback option. Then you can control the program flow by invoking your callback. Don't forget to call it in every case, otherwise the queue will stuck.