Is calling a function in a function (callback) an asynchronous operation in JS?

Question

JavaScript

I am studying asynchronous programming in JS, tell me if callback is an "asynchronous operation" in JS?
...callback.apply(callbackObj, [firstName, lastName]);...

( function () {
    "use strict" ;

    var clientData = {
        id : 94545,
        fullName : "Not Set",
        setUserName : function (firstName , lastName) {
            this. fullName = firstName + " " + lastName;
        }
    };
 
    function getUserInput(firstName, lastName, callback , callbackObj) {
        //Вызов метода. Вызывается ли данный метод асинхронно?
        callback.apply(callbackObj, [firstName, lastName]);
        // Some action after callback running
    }
 
    getUserInput ("Barack", "Obama", clientData.setUserName, clientData );
    console.log( clientData.fullName);
}());

Answer 1

Of course not. You simply call the function and ensure that this when it is executed will have a reference to the first parameter passed.
By itself, calling any method is synchronous code. Be it at least setTimeout() , at least new XMLHttpRequest().send() .