Are Node.js scripts asynchronously executed?

[Thejdeep]

For example, is my plan A has Task A and Task B both running node.js scripts

Lets assume :

Task A makes a network request and in the callback calls a console.log("Done A");

Task B just logs console.log("Done B");

According to what I am seeing in the Bamboo logs, the order is correctly displayed - 

Done A

Done B

I am just wondering how Bamboo handles these async scripts. How does it know for how much time to wait?