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global variable availability


jimfog

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Below you will see code related to a backbone view(simplified)...I have not included some code so as to keep things as simple as possible-I think the omitted code will not affect what I am trying to convey here.

var EventView = Backbone.View.extend({        selestrt: null,        events: {"change #timesfrom": "changefrom",             },      dropfrom:function(selestrt,test)        {  selestrt;//global        },      changefrom:function(){       selestrt;//global         }});

I have declared a global variable selestrt so that his can be available at BOTH functions...and here is where the problem manifests itself.

The dropfrom function is used to build a dropdown menu(selestrt is a UNIX timestamp that is used to create the menu).

 

Changefrom is called when the user makes s selection from the dropdown menu(you can see also the code corresponding to the event)

#timesfrom is the id of the div where the menu is included.

 

Unfortunately when changefrom is called selestrt is considered undefined.

 

I did not include any HTML or prepare a fiddle for that matter cause I want to portray the problem as simple as possible-but if you consider it necessary I will do it.

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from what you've shown, selstart is not global. it's just a property of the object you are passing into Backbone.View.extend.

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from what you've shown, selstart is not global. it's just a property of the object you are passing into Backbone.View.extend.

This is the stackoverflow topic from where I got the above....http://stackoverflow.com/questions/9411896/using-global-variables-in-backbone-js#comment38377574_9411976

 

I have forgotten to put the variable inside the initialize function...still the problem remains.Here, how the code is now...again simplified:

 var EventView = Backbone.View.extend({        selestrt: null,        initialize: function() {            _.bindAll(this);       this.selestrt;            },      events: {"change #timesfrom": "changefrom",             },      dropfrom:function(selestrt,test)        {  selestrt;//global        },      changefrom:function(){       selestrt;//global         }});

To get an understanding of what I am trying to do:

 

When dropfrom is called,the dropdown menu appears with a preselected vaue...(the UNIX timestamp, which is stored at selestrt ).

 

I want this to available at the changefrom function,which(as stated) is called when the user goes to change/selects a value from the drop menu.

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What you are doing makes no sense to me. A global named selestrt cannot be accessed if you have a local property named...

 selestrt: null,

...also what is this line supposed to do?

this.selestrt;

...or what is this line supposed to do?

selestrt;//global
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What you are doing makes no sense to me. A global named selestrt cannot be accessed if you have a local property named...

 selestrt: null,

...also what is this line supposed to do?

this.selestrt;

...or what is this line supposed to do?

selestrt;//global

 

Regarding the first 2 lines...I just copied the code from StackOverflow and begun testing.

 

And about the last line....if you notice it is INSIDE the changefrom function,cause I wanted to be available there.

Of course there is more code there...I just omitted it for reasons of simplicity,the variable as it is there,"alone",of course it does not make sense.

I can post the whole code if you want.

Here is the error message as it appears in the console....http://1drv.ms/1sUJQoH

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nothing?

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I am not familiar with Backbone but you have selestrt declared as a property and also as a parameter and then you put it on a line by itself. Try...

console.log(this.selestrt);
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I am not familiar with Backbone but you have selestrt declared as a property and also as a parameter and then you put it on a line by itself.

As already stated, I just followed the stackoverflow post...

Maybe I should prepare a jsfiddle demo.

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If you want selestrt to be availible inside changefrom(), simply prepend it with a "this."

 

they're both properties to the same object, so the "this" inside a function should point the the proper reference.

  changefrom:function(){    this.selestrt;      // NOT global, but a local variable to the       // object the function is assigned with  }

its not "technically" a global variable per se, but every function in the object can still access the variable.

 

I just read that stackoverflow link and even in their answer, they would use the "this" keyword. That's important.

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If you want selestrt to be availible inside changefrom(), simply prepend it with a "this."

 

they're both properties to the same object, so the "this" inside a function should point the the proper reference.

  changefrom:function(){    this.selestrt;      // NOT global, but a local variable to the       // object the function is assigned with  }

its not "technically" a global variable per se, but every function in the object can still access the variable.

 

I just read that stackoverflow link and even in their answer, they would use the "this" keyword. That's important.

Yes,your solution worked....by making a minor adjustment though:

 this.selestrt=selestrt;

P.S It had not occurred to me that backbone models are actually objects(with properties/methods)...I know that this can easily be deducted,nonetheless I hadn't noticed it(although it is apparent)

Edited by jimfog
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