The aura method discussed in the preceding section has return statements and is synchronous. Most often, when you are working with server-side code to fetch values using @AuraEnabled methods, it's asynchronous. If you use return statements, you will notice that aura methods run before the server returns the value; so, it's important to pass the function and use callback (https://developer.mozilla.org/en-US/docs/Glossary/Callback_function).
Let's demonstrate how callback works, with the help of the following example code.
Let's create a child component (we will assume it's a component API, which can be reused across various components). The controller code to fetch the contacts is as follows:
public with ...
