同一JavaScript类[Prototype]中的调用方法

Question

I've created a class in Javscript using the prototype Class.Create complete with the initialize function and a few other functions. However, in one of my functions I want to reference another function in the same class, but cannot seem to get the syntax correct.

eg

    var sampleClass = Class.create({

            initialize: function(){

                //do the init work here

        },

        functionA: function(){

            //do some more stuff here
        }
        functionB: function(){
            //Do some stuff
            functionA()
        }
}

I've tried calling functionA() , this.functionA() but nothing works I just get errors. I know how to call the functions externally when the class has been instantiated, but not reference a function from within the class itself.

Thanks

Answer 1

this.functionA()

would be the correct way to call the object's method from within another method of the same object.

but nothing works I just get errors

What errors? If you are getting 'property functionA not found', then the probability is that this is pointing in the wrong place. Use Firebug or some alert ​s to check what it is. A common problem is that you've detached the method's function from the owner object and passed it to something else:

element.onclick= this.functionB;

when functionB is called back in this case, this will be unset and so will default (very unhelpfully, for debugging) to window . This happens because object.methodname in JavaScript, unlike many other modern scripting languages, only gives you an unbound function object and not a bound method.

The simple way to preserve this , introduced by Prototype and now a standardised part of JavaScript (coming soon to a browser script engine near you), is function.bind :

element.onclick= this.functionB.bind(this);

Answer 2

Agreed with bobince, except you'll want to use the Event.observe() syntax for attaching event handlers rather than assigning to the element's onclick property. Example:

element.observe('click', this.functionB.bind(this));