Using named functions for callbacks

Question

I have a major problem with profiling in javascript with anonymous functions, I have always many anonymous functions - most of them are callbacks - and It makes analyzing results of profiler very hard for me.

Finally I decided to use named functions for callbacks, like this:

var f = function(callback) {
    // Do something ...
    callback();
}

f(function named_function() {
    console.log('Sample callback function!');
});

I want to know that will I have any problems after making this change in my codes? And will this type of function definition and passing reserve the name (named_function) anywhere?

Answer 1

The name will only be available inside the scope of the named function expression.

But there is a problem in IE 8 and lower. It will leak out to the outer scope, and will actually create a different function object, so you should nullify it if that's a problem.

f(function named_function() {
    console.log('Sample callback function!');
});
var named_function = null;

See this article for more information: Named function expressions demystified

Or you could create it like this to solve the IE issue.

f(function() {
    return function named_function() {
        console.log('Sample callback function!');
    };
}());

But that's a little ugly.

Answer 2

If you pass anonymous functions like that, the name will exist inside the function itself.

It will not exist in any other scope.

var f = function(callback) {
    // Do something ...
    callback();
}

f(function named_function() {
    console.log(named_function); // Logs the function
    console.log('Sample callback function!');
});

console.log(named_function);​ // Error: named_function is undefined