Calling functions within an object

Question

I've created an object as follows.

function StartObj() {
   var events = {
      a: function() {
         alert("hello");
      },
      b = function() {
         lightbox(events.a);
      }
   };

   this.main = function() {
      $("#objId").click(events.b);
   }

}

$(document).ready(function(){
      var _start_obj = new StartObj();
      _start_obj.main();
   });

And in another file,

function lightbox(funcPtr) {
   alert(funcPtr);
}

The alert is reporting funcPtr is undefined; also the google chrome console.

How are you calling it? These are just definitions. (I think your issue might be with what this means inside your b function.) — Kevin Boucher
– Kevin Boucher, Commented Oct 11, 2012 at 15:54

udidu · Accepted Answer · 2012-10-11 15:55:59Z

2

Are you sure? this is works for me... I just added the call to x.b() to start it up

var x = {

a: function() {
   alert("hello");
},

b: function() {
       var that = this;
       mayhem(that.a);
    }

}

function mayhem(funcPtr)
{
   funcPtr();
}

x.b();

answered Oct 11, 2012 at 15:55

udidu

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1 Comment

viji Over a year ago

I'm not calling x.b straight away. I'm initializing an object and then I'm calling.

Denys Séguret · Accepted Answer · 2012-10-11 16:32:11Z

1

You probably don't do what you think you do.

The line var that = this; is useless and this, anyway, isn't really x but the receiver of the x.b function.

This means that if you do

x.b();

this works

but if you do

var f = x.b;
f();

this doesn't work.

If you want to ensure that the working of x.b isn't dependent of the receiver of the function, you may do this :

var x = function(){
    var x ={
       a: function() {
           alert("hello");
       } 
    };
    x.b = function() {
        mayhem(x.a);
    }
    return x;
}();

An alternative would be to create a constructor and make x using the new operator.

Regarding you edit :

If you want main to be accessible, do this :

function StartObj() {
   var events = {
      a: function() {
         alert("hello");
      }
   };

   events.b = function() {
         lightbox(events.a);
   };

   this.main = function() {
      $("#objId").click(events.b);
   }
}

edited Oct 11, 2012 at 16:32

answered Oct 11, 2012 at 16:00

Denys Séguret

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7 Comments

viji Over a year ago

Can you plz review my question ?

Denys Séguret Over a year ago

See edit. But what do you want to alert ? the function code or just "hello" ?

viji Over a year ago

Actually, the parameter I'm passing inside the function is a callback function which will be called when the lightbox initializes itself. I'm just checking with a function stub.

Bergi Over a year ago

@dystroy: Your last code with the prototype doesn't work, because events is local to the constructor

Denys Séguret Over a year ago

@Bergi Right : too many copy-paste... As it's yet confused enough and probably not relevant I remove the prototype version...

|

Bergi · Accepted Answer · 2012-10-11 16:29:00Z

0

You've screwed up your StartObj constructor - it does not return an object with a main method, main is just a local function. Also, you've got a closing brace too much after the assignment of events.b. This should work:

function StartObj() {
   var events = {
        a: function() {
            alert("hello");
        },
        b: function() {
            lightbox(events.a);
        }
    };

    this.main = function main() {
        $("#objId").click(events.b);
    }   
}

Also, make sure that lightbox is really globally available - check your error console.

answered Oct 11, 2012 at 16:29

Bergi

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1 Comment

viji Over a year ago

Hey. Thanks for the reply dude. I"ve put the closing bracket properly. But when pasting here, I made a mistake

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