We Keep Coding

How can I get the Function object in the body of such function?

Is there a way to get the Function object, while the function is executing?
I am assigning properties to my function, and want to access them. "this" doesn't help. Something like:
a.b=function(){...code...};
a.b.c=100;
I want to access a.b.c from the code in the function, without knowing its own name. "this" refers to a. How can get b?
I tried binding the function to his own object, but I couldn't.
Thank you.
I'm adding this example, I have to repeat after several different "theString" and "someSpecificValues":
Object.defineProperty(theObject, theString, {get: function(...){...}.bind(theObject, someSpecificValues), configurable: true});

You can use a named function expression for this:
var a = {};
a.b = function myFunc() {
console.log(myFunc.c);
};
a.b.c = 100;
a.b();
It allows code inside the function to access the function itself, but does not add the identifier to the enclosing scope.
Edit: Here is a more elaborate example of how the name myFunc only exists within the function:
var a = {};
a.b = function myFunc() {
console.log(myFunc.c);
};
a.b.c = 100;
a.d = function myFunc() {
console.log(myFunc.c);
};
a.d.c = 300;
a.b(); // logs 100
a.d(); // logs 300
console.log(typeof myFunc); // logs "undefined"
// create a myFunc variable
var myFunc = function() {
console.log("nooooooo!!!!");
};
a.b(); // STILL logs 100. the myFunc variable in this scope
// has no effect on the myFunc name that a.b uses
function callFunc(theFunc) {
theFunc();
}
callFunc(a.d); // STILL logs 300
// ===========================
function returnNamedFunction () {
return function myFunc() {
console.log(myFunc.c);
};
}
var iGotAFunction = returnNamedFunction();
iGotAFunction.c = 700;
iGotAFunction(); // logs 700
In the case when you cannot use a named function expression, e.g. when you are using .bind() on it, then an IIFE will suffice most of the time:
var myObj = {};
myObj.theFunc = (function () {
var f = function (arg1, arg2) {
console.log(this.theProp);
console.log(arg1);
console.log(arg2);
console.log(f.lista);
}.bind(myObj, "A!");
return f;
})();
myObj.theProp = "B!";
myObj.theFunc.lista = [1, 2, 3];
myObj.theFunc("C!");

There are two ways to get current function.
One is "almost deprecated" usage of arguments.callee. In function body it always refers to this function.
var a = {};
a.b = function () {
console.log(arguments.callee.c);
};
a.b.c = 100;
a.b();
arguments.callee is forbidden in strict mode. Reference.
The second one is using named function expression as JLRishe pointed.
arguments.callee pros and cons
Advantages:
it can be safely used with bound functions (arguments.callee refers to bound function)
it can be used with functions created using new Function
Disadvantages:
it can slow your program due to disabling certain optimisations
it's considered as almost deprecated
it can't be used in strict mode
Named function expression pros and cons
Advantages:
it's faster than arguments.callee
it's easier to understand how it works
Disadvantages:
it won't work as expected with bound functions (functionName will refer to original function, not bound one)
it can't be used in functions created with new Function

'this' keyword doesn’t always refer to the object on which a method is defined, but instead can change based on specific contexts. How?

I was going through this article http://dev.opera.com/articles/view/objects-in-javascript/
where I read "'this' keyword doesn’t always refer to the object on which a method is defined, but instead can change based on specific contexts."
I couldn't find any example in which 'this' does not refer to the object on a method is defined....please gimme an example if possible

One example that you could realistically run into and not expect this result:
var obj = {
testFunc : function(){
alert("testFunc: " + this);
}
}
obj.testFunc(); // this is the object
setTimeout(obj.testFunc, 1000); // this is window
http://jsfiddle.net/t7ycd/

There are many way to change context. jsfiddle
using bind: (not supported by older IE browsers (IE < 9))
var obj = {};
function fun1(){};
obj2 = {};
obj2.fun1 = fun1.bind(obj);
obj2.fun1(); // context inside fun1 would be obj.
Using apply or call.
var obj = {};
function fun1(){};
obj2 = {};
obj2.fun1 = function(){
fun1.apply(obj, arguments);
//or fun1.call(obj, ar1, arg2,...);
};
obj2.fun1(); // context inside fun1 would be obj.

Here is one way
var a = {};
a.foo = function(){ console.log(this); }
a.foo(); // object a
a.foo.call(window); // window object

If you call a method in class B from class A, the 'this' will refer to the class that is calling the method - A, not the class that it is in.

Here is an example taken directly from the Mozilla documentation
https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Operators/this
var o = {prop: 37};
function independent() {
return this.prop;
}
o.f = independent;
console.log(o.f()); // logs 37
So the function independent is defined in the global context, but is then attached to an object. When it is invoked on that object the context becomes the object on which the function is invoked rather than the object on which the function is defined.
You can achieve similar results using the javascript call and bind methods, and using anonymous functions.

like this
var MyObject = function()
{
this.initialize();
}
MyObject.prototype.SomeMethod = function()
{
//common fix is to use
//var self = this;
(function(){
//this has lost scope
//self will retain the this scope that was desired
})();
}

OOP. Calling methods from within methods

How do I call class methods from functions within the class? My code is:
var myExtension = {
init: function() {
// Call onPageLoad
},
onPageLoad: function() {
// Do something
},
}
I've tried ...
onPageLoad();
... from within the init method but it's saying it's not defined.
I'm not having much luck with google because I don't understand the syntax used. All the JS OOP examples I find online are in a different format. I'm using the format Mozilla use for extension development.

The object the current method was invoked on is available via the special variable this. Any time you call a method on an object, this will refer, within the method, to the object.
var myExtension = {
init: function() {
this.onPageLoad();
},
onPageLoad: function() {
// Do something
},
};
this always refers to the calling object rather than the object the function is defined on or is a property of.
value = 'global';
var ob0 = {
value: 'foo',
val: function() {
return this.value;
},
},
ob1 = {value: 'bar'},
ob2 = {value: 'baz'};
ob0.val(); // 'foo'
ob1.val = ob0.foo;
ob1.val(); // 'bar'
ob0.val.call(ob2); // 'baz'
var val = ob0.val;
val(); // 'global'
In the last case, val is executed as a free function (a function that isn't bound to an object, i.e. not a method), in which case this takes on the value of the global object (which is window in web browsers) within the execution of val. Global variables are actually properties of the global object, hence val() returns 'global' (the value of the global variable named value). Since global variables are actually properties of the global object, you can view free functions as actually being methods of the global object. From this viewpoint, the last two lines (when executed in global scope) are equivalent to:
window.val = ob0.val;
window.val();
This viewpoint doesn't exactly match the reality of scoping, though you'll only notice the difference within functions. In a function, window.val = ... will create a global while var val won't.
value = 'global';
var ob0 = {
value: 'foo',
val: function() {
return this.value;
},
};
function lcl() {
var val = ob0.val; // doesn't set a global named `val`
return val(); // 'global'
}
lcl(); // 'global'
val(); // error; nothing named 'val'
function glbl() {
window.val = ob0.val; // sets a global named `val`
return window.val(); // 'global'
}
glbl(); // 'global'
val(); // 'global'
See MDN's reference page for more on the call method used above. For more on the this variable, see "JavaScript “this” keyword" and "How does “this” keyword work within a JavaScript object literal?"

Assuming that you have called init like this:
myExtension.init();
then it should be:
init: function() {
// before
this.onPageLoad();
// after
}
But in Javascript functions are not actually bound to objects and you can call any function on any other object, like this:
myExtension.init.call(anotherObject); // or
myExtension.init.apply(anotherObject);
In this example this within init would be anotherObject, which doesn't have onPageLoad defined. If you want to support this kind of usage you'll have to manually reference the initial object:
init: function() {
// before
myExtension.onPageLoad();
// after
}

In Javascript you need to explicitly mention the this
this.onPageLoad()
The same is also true for other member variables (remember that in Javascript methods are just member variables that happen to be functions)
this.memberVariable

Have you considered a closure, instead?
For example:
var myExtension = ( function() {
var me = {};
var private_thingy = "abcDEFG123";
var onPageLoad = function() {
// do page loading business
alert( private_thingy );
}
me.onPageLoad = onPageLoad;
var init = function() {
onPageLoad();
}
me.init = init;
return me;
})();
///////////////
myExtension.private_thingy = "DIDDLED!";
// will NOT modify the private_thingy declared within the closure
myExtension.init(); // will work fine.
Anything you define within the closure is available within the closure at all times, and when implemented carefully will yield private members not accessible to users of the object. Only members that you explicitly export - e.g., the me.xxx = xxx lines - are publicly available.
Thus, when onPageLoad executes, "abcDEFG123" will be displayed in the alert, not "DIDDLED!". Users of the object can modify properties using the dot operator until the cows come home; what's not made public by the closure, however, can never be modified: even if the user reassigns a function on the public interface, calls to the private function from within the closure will always point to the function defined within the closure.
The important part: it unties you from the constant use of this (unless you really want to use it; save your fingers for more important typing!).
Give it a shot. And have a look at Javascript: The Good Parts by Crockford.

How does 'call' work in javascript?

I have a question on 'call' in javascript.
var humanWithHand = function(){
this.raiseHand = function(){
alert("raise hand");
}
}
var humanWithFoot = function(){
this.raiseFoot = function(){
alert("raise foot");
}
}
var human = function(){
humanWithHand.call( this );
humanWithFoot.call( this );
}
var test = new human();
so..when I use 'call' as humanWithHand.call(this), what happens internally?
does humanWithHand variable copies (or points?) its properties and members to human variable's prototype?

Yehuda Katz has a good writeup of JavaScript's Function#call method. His writeup should answer your question, and many followup questions besides.
When you call a function directly, using the general syntax:
var foo = function() {
console.log("foo");
return this;
};
foo(); // evaluates to `window`
Then this inside the function call is whatever this is outside the function call. By default, in the browser, this outside any function calls is window. So inside the function call as above, this is also by default window.
When you call a function using the method-call syntax:
var bar = {
foo: function() {
console.log("foo");
return this;
}
};
bar.foo(); // evaluates to `bar`
Then this inside the function call is the object to the left of the rightmost period: in this case, bar.
We can simulate this situation using call.
When you set up a function outside an object and want to call it with this inside the function call set to an object, you can:
var foo = function() {
console.log("foo");
return this;
}
var bar = { };
foo.call(bar); // evaluates to `bar`
You can use this technique to pass arguments as well:
var foo = function(arg1, arg2) {
console.log("foo");
return arg1 + arg2;
}
var bar = { };
foo.call(bar, "abc", "xyz"); // evaluates to `"abcxyz"`

.call() sets the this value and then calls the function with the arguments you passed to .call(). You use .call() instead of just calling the function directly when you want to set the this value inside the called function rather than let it be set to whatever javascript would normally set it to.
.apply() is a sister function. It can also set the this value and it can take arguments in an array so it can be used when you are trying to pass a variable argument list from some other function call or when you're constructing an argument list programmatically which may have different numbers of arguments depending upon the situation.

How the JavaScript this keyword works?

I have been doing some JavaScript development and I encountered this problem. Consider the following code
var obj = {};
obj.bind = function () {
console.info(this);
};
obj.bind();
I'm running the code on the FireBug JavaScript console. The expected result is that this displays a reference to the object in the console.
It actually displays undefined.
But, when I make this change to my code
var obj = {};
obj.bind = function () {
this.x = 'x';
console.info(this);
};
obj.bind();
Now the console displays the expected value of this, which is a reference to the obj object.
Why does this happen?

undefined is the return value of the function, which you'll get because you're not returning a value explicitly.
In both Chrome and Firebug, it correctly displays the Object in the console before the return value undefined.
So if you do:
var obj = {};
obj.bind = function () {
console.info(this);
return "foo";
};
obj.bind();
...you should see something like:
Object { }
"foo"
If Firebug is not displaying the Object when it is empty, you may need to check to make sure you're using the most current version.

In your example, "this" should be obj, just as some commenters pointed out. Here are the details that explain why --
In Javascript, the value of "this" changes depending on how you call the function:
When a function is stored as a property on an object, and you invoke that function by calling obj.foo(), "this" will be obj.
EX:
var obj = {
x: 1,
increment: function() {
this.x = this.x + 1;
};
obj.increment(); // Makes "this" be obj
When you invoke a function using syntax that does not refer to any owning object, "this" will be the global environment.
EX:
function someFunc(a, b) {
return a + b; // If you were to refer to "this" here, it would be the global env.
}
someFunc(5, 6);
When you invoke a function as if it were a constructor by using the new operator, a new object will be instantiated for you, and "this" will point to that new object.
EX:
function SomeConstructor() {
this.x = 42; // under the hood, a new object was instantiated for you, and "this" was set to it.
}
var result = new SomeConstructor(); // note the "new" keyword
// result will be { x:42 }
When you use call() or apply(), you can control what "this" is.
(No example here since it's fairly far from your question. Look up docs for apply() or call() for an example.)