Question

Is there any advantage of wrapping a function with an anonymous function?
I mean a particular example:

function asyncFuntion(callback) {
    setTimeout(callback, 6000);
};

asyncFuntion(function() {
    console.log('Calling after 6 s.');
});   

and with the wrapped function:

function asyncFuntion(callback) {
    setTimeout(function() {
        callback();
    }, 6000);
};

asyncFuntion(function() {
    console.log('Calling after 6 s.');
});

In both cases output is the same. So is there any difference?
The second version is what I found learning js.
I realize that such a form is useful when we need closures but here?

Answer 1

The second form allows you to pass arguments to callback, whereas the first form doesn’t.

// 1st form
setTimeout(callback("This doesn't work as you might expect"), 6000);

// 2nd form
setTimeout(function() {
    callback("This works");
}, 6000);

If you’re not passing arguments, then there is no advantage in wrapping the function whatsoever.

---

To be more thorough, Function.prototype.bind can help us with the first form:

setTimeout(callback.bind(this, "This works fine too"), 6000); 

// Even with Richard JP Le Guen's example by specifying the thisObj
setTimeout(customObj.alert.bind(customObj), 6000);

However, you will need to provide this method to browsers that don’t support the event (namely Opera, Safari and IE 8, 7, 6). The code to shim the method is available on the MDN documentation page.