How to Pass Custom Parameters to Event Handler

Well, generaly, closures allow you to pass "hidden" parameters to a function:

function make_event_handler(customData){
    return function(evt){
        //customData can be used here
        //just like any other normal variable
        console.log(customData);
    }
}

So when connecting an event in dojo:

dojo.connect(node, 'onclick', make_event_handler(17));

Another possibility that I like a lot is using dojo.partial / dojo.hitch to create the closures for you.

function event_handler(customData, evt){
     ///
}

dojo.connect(node, 'onclick', dojo.partial(event_handler, 17))

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Note that all of these these required your event handlers to be created with passing the extra parameter(s) in mind. I don't know if you can do a more direct translation of the JQuery code since that would require extra massaging of the evt variable and I don't think dojo does that.