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overriding fullcalendar javascript functions which is in another script

I am newbie in js and I want to override/overwrite some fullcalendar functions from another script (my-fullcalendar.js) to make some changes in it for myself. for example function names are :
formatRange and oldMomentFormat.
formatRange is accessible from this.$.fullCalendar.formatRange but oldMomentFormat is not accessible via this kind of chain. But even when I do something like this in my-fullcalendar.js:
;(function () {
function MyformatRange(date1, date2, formatStr, separator, isRTL) {
console.log( "MyformatRange");
//other parts is exactly the same
// ...
}
this.$.fullCalendar.formatRange=MyformatRange;
console.log(this);
})();
nothing happens because no log is generated and even line by line tracing does not pass from here. but when observing "this" in console log MyformatRange replaced by original formatRange.
another problem is how can I override/overwrite oldMomentFormat function which is not in window hierarchy to access (or I can not find it) ??

OK, let's simplify the problem. In essence, you have this situation:
var makeFunObject = function () {
var doSomething = function (msg) {
console.log(msg);
};
var haveFun = function () {
doSomething( "fun!");
};
return {
doSomething : doSomething,
haveFun : haveFun
};
};
In other words you have a function that is creating a closure. Inside that closure are two "private" functions, one of which calls the other. But both functions seem to be "exposed" in the returned object.
You write some code:
var myFunObject = makeFunObject();
myFunObject.haveFun(); // fun!
Yep, seems to work just fine. Now let's replace the doSomething function in that returned object and call haveFun again:
myFunObject.doSomething = function (msg) {
console.log("My new function: " + msg);
};
myFunObject.haveFun(); // fun! <== wait what?
But wait! The new replacement function is not being called! That's right: the haveFun function was expressly written to call the internal function. It in fact knows nothing about the exposed function in the object at all.
That's because you cannot replace the internal, private function in this way (you cannot replace it at all, in fact, not without altering the original code).
Now draw back to the FullCalendar code: you are replacing the external function in the object, but the internal function is the one that is called by every other function inside FullCalendar.

I realize this is an old question, but I was butting my head against this same problem when I wanted to override the getEventTimeText function.
I was able to accomplish this, from inside my own JS file, like so:
$.fullCalendar.Grid.mixin({
getEventTimeText: function (range, formatStr, displayEnd) {
//custom version of this function
}
});
So, in terms of the function you were trying to override, you should be able to do it with:
$.fullCalendar.View.mixin({
formatRange: function (range, formatStr, separator) {
//custom formatRange function
}
});
Note: Make sure this runs before where you actually create the calendar. Also note that you need to make sure to override the function in the right place. For example, getEventTimeText was in $.fullCalendar.Grid, while formatRange is in $.fullCalendar.View.
Hopefully this helps other people who end up on this question.

Is it possible to get the local variable and parameter values with window.onerror

I have a simple javascript error logging mechanism in place and it looks somewhhat like this:
window.onerror = function (ErrorMsg, Url, LineNumber, Col, Error) {
// ajax these to the server, including Error.stack}
The problem is that I'd also like to get the value of the local variables and function parameters when the error occurred. Is this even possible?
I'm thinking about modifying the Function prototype so that each time a function runs, its arguments are stored in a global array of strings and then the error handler would just add this array to the ajax call. Can JavaScript do this?

#1 Can local scope be recovered in onerror() without black magic?
Without this being bound in the scope of window.onerror() or the surrounding variables being directly accessible, it's impossible to regain access to the variables you had set.
What you're mostly wanting access to is this.arguments or arguments or the equivalent, but that's destroyed. Any hope of obtaining a key-value associative array or hash-like object would involve meta-programming ( i.e. reading the function definition to obtain the variable names, and obtaining an exception report to attempt to salvage data ).
See this answer for more on something similar:
Getting All Variables In Scope
But this "lacking functionality" is a good thing:
If you could gain access to what you're asking for, that would likely be a fault in the Javascript engine. Why? Because the variable states and contents themselves are what caused the exception/error, assuming bad code wasn't the issue to begin with.
In other words, if you could get access to a faulty variable, that might be a door into an infinite loop:
Failure due to variable contents.
Error handler triggered.
Trace contents of variable.
Failure due to variable contents.
Error handler triggered.
Trace contents of variable.
Etc.
#2 Can Javascript store all arguments of every function call by voodoo?
Yes. It can. This is probably a really bad idea ( see #1 ) but it is possible. Here is a pointer on where to start:
Is there a way to wrap all JavaScript methods with a function?
From there, what you're wanting to do is push this.arguments or equivalent to a stack of function calls. But again, this is approaching insanity for many reasons. Not the least of which is the need to duplicate all the values, lest you reference mutated variables, or be unable to access the data at all... and like I said above, the problem of bad data in general. But still, it is possible.

Is this even possible?
No. A stack trace is proof that the stack has unwound, all stack frames and all the local variables they contained are gone. As for getting the name of a variable, that is not even possible at run time.

To start off i accept #Tomalak completely.
I was also put in your situation where i needed to debug a remote running app in case of crash.
As a work around I have forked my code for you in a fiddler. Please modify according to your need.
Caveat: You have to wrap the function body with try{..}catch(e){..} as illustrated in the fiddler code.
Please read the inline comments for understanding.
window.onerror = function (errorMsg, url, lineNumber, column, errorObj) {
console.log(errorObj);
}
window.addEventListener("reportOnError", function(e){
console.log(e.detail);
/*Send to the server or any listeners for analysis.*/
//Http.send(e.detail);
});
function ExceptionReport(ex, args, scope) {
var self = {};
self.message = ex.message;
self.stack = ex.stack;
self.name = ex.name;
self.whoCalled = args.callee.caller.name == "" ? "Window": args.callee.caller.name;
self.errorInFunction = args.callee.name;
self.instanceOf = scope.constructor;
self.KeyPairValues = getParamNames(arguments.callee.caller.toString(), Array.prototype.slice.call(args)); //Contains the parameters value set during runtime
window.dispatchEvent(new CustomEvent('reportOnError', {'detail':self}));
}
//Utilties
function getParamNames(fnBody, values) {
var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg,
ARGUMENT_NAMES = /([^\s,]+)/g,
result = fnBody.slice(fnBody.indexOf('(')+1, fnBody.indexOf(')')).match(ARGUMENT_NAMES),
obj={};
fnBody.replace(STRIP_COMMENTS, '');
if(result !== null){
for(var i=0; i < result.length; i++){
obj[result[i]] = values.length !==0 ? values[i] : null;
}
}else{
obj = null;
}
return obj;
}
/*
This is a testing/sample function that throws the error
*/
function testing(a,b,c){
try{
dummy(1,2) ; //This line throws the error as reference error.
}catch(e){
ExceptionReport(e, arguments, this);
}
}
//Class Emulation: For instanceof illustration.
function testingClass(){
this.testing = testing;
}
//Named self executing function: This calls the function
var myvar = (function myvar(){
testing(1,2,3);
})();
//Illustrating instanceof in exception
var myVar2 = new testingClass();
myVar2.testing(1,2,3);
//Calling from global scope this is Window
testing(1,2,3);
//Without variables
testing();
I have used examples to illustrate the behavior of functions called in different circumstances.
Below signifies the varialble used for
self.KeyPairValues : Used to store the function parameter set/passed during runtime
self.errorInFunction : This stores the name of the function error was caused in.
self.whoCalled : This stores the function name that invoked the defective function
self.instanceOf : This stores the name of the instance is called creating a new instance.
Other variables are same as in Error object

The others answers here are spot on, but I might be able to offer a suggestion for a slightly different way to accomplish this. Instead of trying to track all scope in your program, why not add a tagging function that tracks the scope of one function's parameters without affecting the runtime of the function. For for example:
var globalRecord = {};
function record(name, fn) {
return function () {
var args = [].slice.call(arguments);
var record = globalRecord[name] = {
args: args,
arg: {}
};
args.unshift(function (name, value) {
return record[name] = value;
});
fn.apply(args, arguments);
}
}
// Then, you track variables like this
var func = record("func", function (record, a, b, c) {
record("a", a); // named parameters are accessible now
record("b", b); // if some error occurs in the function body
return a + b + c;
});
// Calling func still behaves as before.
func(1, 2, 3);
// Errors handled like this:
window.onerror = function () {
globalRecord.func.args; // ==> last set of arguments past to function
globalRecord.func.arg.a; // specific arguments recorded with names
};
You could even use this method to track scope without using a function by anonymously calling the recorded function.
record("test", function (record) {
var a = record("a", /* whatever */);
var b = record("b", /* ... */ );
// do scope specific stuff that might fail
})();
Of course, this isn't a polished implementation by any stretch, but with a little work, I think you might be able to get the behavior you're looking for without any seriously black magic. By selectively adding and removing record calls as the need presents itself, you can have precise control over what is logged without any intrusive hacks.

You can find your answer in this link.
Before taking bundles from the server, you must modify them. For example, to solve your problem, you can do changes in the mentioned link as follows. In the BuildBundleContent Class make this change:
contents.Insert(blockContentIndex,
string.Format("if(customErrorLogging)customErrorLogging({0}, this){1}",
errVariable, hasContent ? ";" : ""));
If in the modules you have to use something like:
var self = this;
You can use:
contents.Insert(blockContentIndex,
string.Format("if(customErrorLogging)customErrorLogging({0}, self ? self : this){1}",
errVariable, hasContent ? ";" : ""));
And in added js file:
"use strict";
var customErrorLogging = function (ex, module) {
console.log(module);
//do something...
};
I hope help you.

Differences when using functions for casper.evaluate

I'm using PhantomJS v2.0 and CasperJS 1.1.0-beta3. I want to query a specific part inside the page DOM.
Here the code that did not work:
function myfunc()
{
return document.querySelector('span[style="color:#50aa50;"]').innerText;
}
var del=this.evaluate(myfunc());
this.echo("value: " + del);
And here the code that did work:
var del=this.evaluate(function()
{
return document.querySelector('span[style="color:#50aa50;"]').innerText;
});
this.echo("value: " + del);
It seems to be the same, but it works different, I don't understand.
And here a code that did also work:
function myfunc()
{
return document.querySelector('span[style="color:#50aa50;"]').innerText;
}
var del=this.evaluate(myfunc);
this.echo("value: " + del);
The difference here, I call the myfunc without the '()'.
Can anyone explain the reason?

The problem is this:
var text = this.evaluate(myfunc());
Functions in JavaScript are first class citizen. You can pass them into other functions. But that's not what you are doing here. You call the function and pass the result into evaluate, but the result is not a function.
Also casper.evaluate() is the page context, and only the page context has access to the document. When you call the function (with ()) essentially before executing casper.evaluate(), you erroneously try to access the document, when it is not possible.
The difference to casper.evaluate(function(){...}); is that the anonymous function is defined and passed into the evaluate() function.
There are cases where a function should be called instead of passed. For example when currying is done, but this is not applicable to casper.evaluate(), because it is sandboxed and the function that is finally run in casper.evaluate() cannot use variables from outside. It must be self contained. So the following code will also not work:
function myFunc2(a){
return function(){
// a is from outer scope so it will be inaccessible in `evaluate`
return a;
};
}
casper.echo(casper.evaluate(myFunc2("asd"))); // null
You should use
var text = this.evaluate(myfunc);
to pass a previously defined function to run in the page context.
It's also not a good idea to use reserved keywords like del as variable names.

Recognising variables while assigning a function to a variable in javascript

In my jQuery scripts, when the user closes a menu with an animation, I have to call a function after the closing animation is finished. I want to assign this function dynamically by calling a function openStrip() with a parameter. My code looks like:
var FUNCTION_JUST_AFTER_MENU_CLOSE = function(){};
function openStrip(stripId){
FUNCTION_JUST_AFTER_MENU_CLOSE = function(){
createStrip(stripId);
});
}
if I call openStrip("aStripId"), I expect FUNCTION_JUST_AFTER_MENU_CLOSE to be:
// #1
function(){
createStrip("aStripId");
}
whereas my current code gives:
//#2
function(){
createStrip(stripId);
}
i.e, the parameter passed to the function openStrip() is lost while assigning the function() to the variable FUNCTION_JUST_AFTER_MENU_CLOSE.
How can I avoid this.
EDIT: I discovered that my code is actually working. The problem was elsewhere. I got confused because when I looked at Chrome's debugger, it was showing me the function definition as is (#2 in above). But when it actually went down executing that function later in the code, it did evaluate the values of the passed argument, and endedup executing #1.
Thanks for the answer though. I am marking it correct because that is perhaps a better way of assigning the function.

The best way is to return a function, from openStrip like this
function openStrip(stripId) {
return function() {
createStrip(stripId);
};
}
For example,
function openStrip(stripId) {
return function() {
console.log(stripId);
};
}
openStrip("aStripId")();
# aStripId
openStrip("bStripId")();
# bStripId
You can even assign the function objects returned to different variables and use them later on
var aStrip = openStrip("aStripId");
aStrip();
# aStripId
aStrip();
# aStripId

Expecting the right calling context (this) in the JavaScript object

Consider this:
window.onload = function () {
myObj.init();
};
var myObj = {
init: function () {
console.log("init: Let's call the callMe method...");
//callMe is not defined...
callMe();
//Works fine!
this.callMe();
},
callMe: function () {
console.log('callMe');
}
};
Since the init function gets called this way (myObj.init), I expect this to be myObj in the init function. And if that is the case, why the callMe function fails? How am I supposed to call the callMe function without using the this context in the init body? (Actually, it's too annoying to call the object methods using this over and over again through the functions. So what's the point of having a single object?)
I would like to know how can I fix this so that the callMe method gets called using the first invocation in the code above?

this is never implicit in JavaScript as it is in some other languages. Although there are ways to do it, like this using the with statement:
init: function () {
console.log("init: Let's call the callMe method...");
// Make `this` implicit (SEE BELOW, not recommended)
with (this) {
// Works
callMe();
}
},
...it's generally a bad idea. Douglas Crockford probably wrote one of the better descriptions of why it's a bad idea, which you can find here. Basically, using with makes it nearly impossible to tell what the code's going to do (and slows the code down, if you do anything else in that with statement that doesn't come from the this object).
This isn't the only way that JavaScript's this is not the same as it is in some other languages. In JavaScript, this is defined entirely by how a function is called, not where the function is defined. When you do this.callMe() (or the equivalent this["callMe"](), or of course foo.callMe(), etc.), two things happen: The function reference is retrieved from the property, and the function is called in a special way to set this to be the object that property came from. If you don't call a function through a property that way, the call doesn't set any particular this value and you get the default (which is the global object; window on browsers). It's the act of making the call that sets what this is. I've explored this in depth in a couple of articles on my blog, here and here.
This (no pun) can be made even clearer if you look at JavaScript's call and apply functions, which are available on all function objects. If I do this:
callMe.call({});
...it'll call the callMe function with a blank object ({}) as this.
So basically, just get used to typing this. :-) It's still useful to have properties and methods associated with an object, even without the syntactic convenience (and confusion!) of an implicit this.

You can also use the module pattern, which captures all private variables inside a closure, so you are free to use them without this, as they're in the same scope. You then pick and choose which methods/variables you want to make public:
var myObj = (function () {
var init = function () {
callMe(); // This now works
};
var callMe = function () {
...
};
// Now choose your public methods (they can even be renamed):
return {
init: init, // Same name
callMyName: callMe // Different name
};
}) ();
Now:
myObj.init(); // Works
myObj.callMyName(); // Works
myObj.callMe(); // Error