Javascript: Calling a method stored in a variable

Question

I am trying to take advantage of Javascript closures by creating a method in one context and storing it in a global variable so that it may be called later from another context.

//Global variable to hold the function
var revertEvent;

//creates the function and assigns it to the global variable
 function createRevertFunction(eventToBeReverted) {

            revertEvent = function () {
                alert("Now Restoring Event");
                $('#calendar').fullCalendar('renderEvent', eventToBeReverted, true);
            }          
  }

So, the "createRevertFunction" holds the state of the original object. That object "eventToBeReverted" is modified down the road after this function is called, so this provides a means to restore the original to the UI without page refresh.

My problem is that I can't seem to call the function in the variable "revertEvent".

I've tried:

revertEvent();
revertEvent.call();
window[revertEvent]();

and none of them work. Any help would be appreciated...!

JaredPar · Accepted Answer · 2010-11-22 19:35:15Z

2

I think the most likely problem here is that you're attempting to call revertEvent before it's been set via createRevertFunction. To verify this change the declaration of revertEvent as follows

var revertEvent = function() { alert('not set yet'); }

This will pop up the alert "not seet yet" in the case it's called before createRevertFunction

answered Nov 22, 2010 at 19:35

JaredPar

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1 Comment

philgiese Over a year ago

I would also think that this is kind of his problem. @cinqoTimo when exactly in you code do you try to call the revertEvent function and when do you call createRevertFunction?

jon_darkstar · Accepted Answer · 2010-11-22 19:33:37Z

2

make createRevertFunction return the interior function. Assign.

var revertEvent;

//returns the function so we can do whatever with it
 function createRevertFunction(eventToBeReverted) {

        return function () {
            alert("Now Restoring Event");
            $('#calendar').fullCalendar('renderEvent', eventToBeReverted, true);
        }          
  }


revertEvent = createRevertFunction(e);

answered Nov 22, 2010 at 19:33

jon_darkstar

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Comments

meder omuraliev · Accepted Answer · 2010-11-22 19:32:10Z

1

>>> var revertEvent; 
undefined
>>> (function() {   revertEvent = function() { alert('hi') }   })();
undefined
>>> revertEvent()

This works for me. Show us your usage of the function, createRevertFunction...

answered Nov 22, 2010 at 19:32

meder omuraliev

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Comments

Lucas Moeskops · Accepted Answer · 2010-11-22 19:31:56Z

0

revertEvent is defined only inside your function and is forgotten afterwards. You will have to save it to a global variable (that is defined outside the function) or rather return the created function and store it.

answered Nov 22, 2010 at 19:31

Lucas Moeskops

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3 Comments

tpow Over a year ago

revertEvent isn't defined in a function, and should have global scope.

John Giotta Over a year ago

revertEvent isn't local scope variable in this example.

Lucas Moeskops Over a year ago

Lol sorry you're right guys, didnt read well enough. Odd then.. will edit when found answer

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