Using both anonymous functions and functions stored in variables as callback arguments JavaScript

Question

I'm not completely clear what this is supposed to mean. I guess my question is if someone could clear this up for me. What I know from Callbacks so far:

function Hello(Callback,a,b){
Callback(a,b);
}

function Hi(a,b){
alert("Hi " + a + b);
}

Hello(Hi,5,6);

Tip: Use lowercase names for everything but constructor functions. — Bergi
– Bergi, Commented Aug 14, 2014 at 0:00
Where did you find this statement? Do you know what an "anonymous function" is? — Bergi
– Bergi, Commented Aug 14, 2014 at 0:00
@Bergi if I'm correct, a Anonymous function is a function with out a name. — SuperCoolDude1337
– SuperCoolDude1337, Commented Aug 14, 2014 at 0:02
Have you ever encountered one in code? How do you thing could this be used here? Are there examples of this in the place where you found this statement (please link it!)? — Bergi
– Bergi, Commented Aug 14, 2014 at 0:03

Charles Smartt · Accepted Answer · 2014-08-14 00:22:47Z

1

In JavaScript, Functions are Objects just like Strings and Numbers, because of that feature you are able to pass Functions as variables into other Functions.

function Hello(Callback,a,b){
Callback(a,b);
}

function Hi(a,b){
alert("Hi " + a + b);
}

Hello(Hi,5,6);

In your snippet, you declare a function called Hello that takes three arguments. The Hello Function will then "call Callback as a Function", actually executing the Hi function that was passed in given your last line of code.

You have to be careful about using Functions like, especially with "this". Since "this" refers to the self-containing object, "this" will actually refer to the Function in certain contexts.

However, that is not what an Anonymous Function is. A modified version of your example:

function Hello(Callback, a, b){
   Callback(a,b);
}
Hello(function(a,b){
  alert("Hi " + a + b);
}, 5, 6);

That function that get's passed in is Anonymous, it isn't named (the JavaScript engine will give it a unique name, but it won't look pretty).

edited Aug 14, 2014 at 0:22

answered Aug 14, 2014 at 0:09

Charles Smartt

3492 silver badges8 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Bergi Over a year ago

this will hardly ever refer to the function itself, no.

Bergi Over a year ago

"Since Functions are objects, you can declare them literally" - huh, what?

Charles Smartt Over a year ago

I guess all functions are really declared literally... unless you something odd like "new Function()" which I think you can actually do...

Bergi Over a year ago

Technically, only function declarations are declared, what you mean is that function expressions can take the place of every arbitrary expression in the code. I've never heard/used the term "function literal", though it seeems to exist

Collectives™ on Stack Overflow

Using both anonymous functions and functions stored in variables as callback arguments JavaScript

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related