reduce no. of lines

I have the following type of many functions so many if condtions are there is there is any way to reduce no. of lines.

enter: function(request, callback, callback1){
    request.on={};
    if(callback==undefined && NodeClientUI.initdata.join!=undefined){
      callback=NodeClientUI.initdata.join;
      request.on.join=function(data){
        callback(data);
      };
    }else if(callback!=undefined ){
      request.on.join=function(data){
        callback(data);
      };
    }
    if(callback1==undefined && NodeClientUI.initdata.occupant!=undefined){
      callback1=NodeClientUI.initdata.occupant;
      request.on.occupant=function(data){
        callback1(data);
      };
    }else if(callback1!=undefined ){
      request.on.occupant=function(data){
        callback1(data);
      };
    }
  };

No of paramerter the callbacks may be increased in many functions.

Please suggest .

Try this:

enter: function(request, callbacks){
    request.on={};
    for(var key in callbacks) {
        var callback = callbacks[key];
        if(callback === undefined) {
            callback = NodeClientUI.initData[key];
        }
        request.on[key]=function(data){
            callback(data);
        }
    }
  };

This permits you to call with callbacks defined as:

var callbacks = {};
callbacks['join'] = function(data) { // join logic ... };
callbacks['occupant'] = function(data) { // occupant logic ... };
callbacks['stuff'] = undefined;  // Takes on value of NodeClientUI.initData.stuff
...

Request would get assigned in the same manner. If you can't pass a map of callbacks in this way, you could create a function which creates a global variable callbacks for you to use inside the method (just ignore the callback parameter passed to enter method and use callbacks instead):

var callbacks = {};
function addCallback(key, callback) {
   callbacks[key] = callback;
}

StackExchange Code Review Q#3434, answer score: 3