Question

I know it’s maybe an fairly easy basic knowledge for you, here I need to ask your help to see whether there is a ‘hole’ behind to improve. Please check the code below, can I set ‘response’ as callback parameter but not callSvc’s? instead of this kinda ‘tricky’ way?

function callSvc(response, callback){
    callback(response);
}

callSvc("I'm a response!",function(param_response){document.write(param_response);});

Thanks..

Update

Maybe this is good enough?

function callSvc(callback) {
    callback("response");
}
callSvc(function(data) {
    document.write(arguments[0]);
});

Answer 1

There shouldn’t be anything tricky about closures in javascript. They are a language feature.

You can avoid the wrapping callSvc function as well, and jump straight into this:

var response = "I'm a response"

var callback = function(){document.write(response);};

The callback function can “see” response as if you passed it as a parameter, since it forms a closure.

callback();  //I'm a response