How to make the definition of a function compatible backwards

backwards_function_definition.js

 // Starting 
 function myFunction(paramA, callback){
   console.log("I'm the old function with paramA and callback.");
   callback(paramA);
 }
 // test
 myFunction("1", function(a){console.log("I should be the parameter: "+a)});
 // returns
 // I'm the old function with paramA and callback.
 // I should be the parameter: 10
 
 // Restyle
 // Note that paramA and callback are the same as the prior version
 function myFunction(paramA, newParamB, newParamC, callback){ //can add as many new 
   // all you have to do is check if the function is called from the previous definition.
   // This happened if the calling arguments are less that <num oldVersion parameters> + 1
   if(arguments.length < 3){
     oldSignature = !!(newParamB && newParamB.constructor && newParamB.call && newParamB.apply);
     if(oldSignature){
      console.warn("WARN: myFunction(paramA, callback) is deprecated! Please use myFunction(paramA, newParamB, newParamC, callback).");
      //here you can decide or not if raise an error... (uncomment code below)
      //throw new Error("ERROR: myFunction(paramA, callback) is deprecated! Please use myFunction(paramA, newParamB, newParamC, callback).");
      //if you want to go on...
      // reassign callback
      callback = newParamB;
      //now you have to provide defaults for newParamB, newParamC
      newParamBDefault = 3; //1 is the "default" for newParamB
      //you can do that for other parameters...
      newParamC =  newParamC || 1; //1 is the "default" for newParamC
     } else{
       throw new Error("ERROR: missing parameters for myFunction(paramA, newParamB, newParamC, callback).");
     }
   }else{
     //just for using the same variable in the function body...
     newParamBDefault = newParamB;
   }
   //here you can do what you want
   paramA = paramA + newParamBDefault - newParamC;
   callback(paramA);
  }
 
 // now the previos call
 myFunction("1", function(a){console.log("I should be the parameter: "+a)});
 // returns
 // WARN: myFunction(paramA, callback) is deprecated! Please use myFunction(paramA, newParamB, newParamC, callback).
 // I should be the parameter: 10