Get event name already being observed

Question

I need to check event name already attached/ observed on an element.

//foo is a button
var isEventObserved = ?// need help in this line
var evnName = ?;// how
If(isEventObserved && evnName === 'my:evn2')
{
     $('foo').observe('my:evn1', mymethod1};
}
else
{
   $('foo').observe('my:env2', mymethod2);
}

Answer 1

Here's what you are looking for

Event.cache[$('foo')._prototypeUID] lists the events registered for the element.

Event.cache[$('foo')._prototypeUID]['element'] is a reference to the element being observed, the rest of the properties in the object are events registered on the element (custom or native)

so for your specific situation

if(Event.cache[$('foo')._prototypeUID]['my:evn2'] != undefined)
{
    $('foo').observe('my:evn1', mymethod1);
}
else
{
    $('foo').observe('my:env2', mymethod2);
}

Please note I tested this with the latest version of Prototype, 1.7.2