Why is arguments.callee.caller.name undefined?

Question

How come this doesn't alert "http://127.0.0.1/sendRequest"? (Available at http://jsfiddle.net/Gq8Wd/52/)

var foo = {
    sendRequest: function() {
        alert(bar.getUrl());
    }
};                    

var bar = {
    getUrl: function() {
        return 'http://127.0.0.1/' + arguments.callee.caller.name;
    }
};

foo.sendRequest();

Answer 1

Putting a value in an object literal, as you're doing, doesn't affect the value at all.

var foo = {
    sendRequest: ...

The function value is only affected by the function expression, which doesn't contain a name.

             ... function() {
        alert(bar.getUrl());
    }

You need to include the name you want in the function expression itself ^[fiddle].

var foo = {
    sendRequest: function sendRequest() {

Answer 2

If you do this:

var foo = {
    sendRequest: function() {
        alert(bar.getUrl());
    }
};                    

var bar = {
    getUrl: function() {
        return  arguments.callee;
    }
};

foo.sendRequest();

You will notice that the function doesn't have name which is true:

function() {

This is anonymous function.

You can name you method : sendRequest: function myMethodName() {

Answer 3

Although the function is stored under the object property foo.sendRequest, and thus can be invoked via foo.sendRequest(), that function itself doesn't actually have a name. That's why arguments.callee.caller.name is empty.

Answer 4

Because the function that is calling the function being called is an anonymous function (and hence, has no name).

Try:

function sendRequest() {
    alert(bar.getUrl());
}

var foo = {
    sendRequest: sendRequest
};                    

var bar = {
    getUrl: function() {
        return 'http://127.0.0.1/' + arguments.callee.caller.name;
    }
};

foo.sendRequest();