Custom javascript event object?

Question

While developing in javascript, I spent tons time to figure out what arguments are passed among functions. So I tried a new method today. I created a simple object then define event name and arguments.

var GreetingEvent = {
    HELLO: 'hello',
    'arguments': {
        name: null
    }
}

// dispatch
// pseudo code
this.fireEvent( new MyEvent(GreetingEvent.HELLO,"myname") );

// listening
// pseudo code
this.listenToEvent(GreetingEvent.HELLO, this.onGreetingEvent);

I'm sure that others already experienced my situation.

What was your situation and solution?

Update:

this is how I'm coding now.

// dispatch
// pseudo code

    this.fireEvent('hello',{name:'myname'});

// listening
// pseudo code

    this.listenToEvent('hello', this.onGreetingEvent);

the problem of this code is that my co-workers must open my code to find out what arguments are being passed to their listeners or they have to use console.log(). That's actually fine. I'm just trying to find a better way.

I'm glad to see you changed your style. I'm baffled as to what that object was buying you. You were still referring to an event name which is a string--why obscure it away? — andyortlieb
– andyortlieb, Commented Feb 14, 2012 at 4:44
@andyortlieb // I had a situation where I had to change my event name. The event was used in many files..so I had to open many files then change the event name then test the code again. Then my co-worker (flash dev) advised me to use an event object instead. I think that's pretty good idea and I just learned that flash, c#, and other languages use events in that way. I really can't answer your question exactly since I'm trying to find out as well. — Moon
– Moon, Commented Feb 14, 2012 at 4:58
That makes some sense from a maintainability standpoint... however I still feel that if you're referencing a named object property on your fires and handlers just for the sake of easily changing the name and maintaining backward compatibility--that's still going to be massively confusing in the long run. The name of your object's property should be just as clear as the name of the event, and if you need to change the name of an event you should probably rename the object property as well, so I guess I'm still missing the point. — andyortlieb
– andyortlieb, Commented Feb 14, 2012 at 16:18
@andyortlieb // same here. I'm missing the point as well. That's why I'm asking suggestions here. When I look at my co-workers (.net and actionscript3) codebases, they're using event objects. They never pass string around and I was told to try that. I guess I should come back to this question few months later with more personal thoughts. — Moon
– Moon, Commented Feb 15, 2012 at 2:33
I don't know about actionscript, and to be honest I don't know much about .net, but is it possible that the event "ID" they're passing is not a string, but some other identifier such as an integer? That would be a good reason for naming a variable or a property on an object so a human can easily identify what a certain event is for. — andyortlieb
– andyortlieb, Commented Feb 15, 2012 at 14:53

Ruan Mendes · Accepted Answer · 2012-02-14 04:42:39Z

Ext-JS does it through JS-doc like annotations. Then their events become part of their published documentation. You may not use their API and won't get the pretty documentation, but you can still use their documentation style and users of your code can just look at the documentation. http://docs.sencha.com/ext-js/4-0/#!/api/Ext.panel.Panel-event-resize

Here's the example from their code of declaring the events.

   me.addEvents(

        /**
         * @event beforeclose
         * Fires before the user closes the panel. Return false from any listener to stop the close event being
         * fired
         * @param {Ext.panel.Panel} panel The Panel object
         */
        'beforeclose',

        /**
         * @event beforeexpand
         * Fires before this panel is expanded. Return false to prevent the expand.
         * @param {Ext.panel.Panel} p The Panel being expanded.
         * @param {Boolean} animate True if the expand is animated, else false.
         */
        "beforeexpand",

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