How to pass params to a callback

Question

I'm trying to find the best practice of implementing the following:
I have 3 functions: manager, httpGet and onsuccess:

1. manager calls the httpGet function and passes the onsuccess function to be called upon success.

2. httpGet makes a request and invokes onsuccesss

3. onsuccess uses needs params from manager

What is the best way to pass and argument from manager to onsuccess without involving httGet?
I was thinking about passing a params object to httpGet which in turn will be passed to onsuccess but I really don't like the idea of passing params to a function that doesn't use them at all.

Answer 1

You mean something like this:

function manager()
{
   var managerParam =0;
   //the anonymous function below is in the scope of manager() so has
   //access to all of managers parameters
   httpGet(function() {
      //this function can use managerParam
      managerParam ++;
   });

  console.log(managerParam === 1); //true
}

function httpGet(onsuccess)
{
   onsuccess();
}

Fiddle

Answer 2

Use a closure:

data = { cool: true };
var yourCallbackFunction = function(httpData, notHttpData){};

var bakedCallback = (function() {
    var _data = data;
    return function(httpResp) {
        yourCallbackFunction(httpResp, _data);
    }
})();
httpGet.onSuccess(bakedCallback);

data is the extra data you want to pass to the function.

In your callback: httpData is the data received from request. NOThttpData is the extra data.

Answer 3

1. Define onsuccess as local function in manager, it may use its arguments and local variables.
2. Pass onsuccess to httpGet.