Convert Cordova-style callbacks to Nodejs-style callbacks

test.js

/**
 * Copy-paste this in your console to test if function works as expected
 **/
function toNodejsFn(cordovaFn,self){
    return function(){
      var args = Array.prototype.slice.call(arguments,0);
      var callback = args.splice(args.length-1,1)[0]; 
      args.push(function onSuccess(){
        var args = Array.prototype.slice.call(arguments, 0);
        args.unshift(null);
        callback.apply(self,args);
      });
      args.push(function onError(){
        var args = Array.prototype.slice.call(arguments, 0);
        // ensure the first argument is not-null
        if(args.length === 0 || !args[0]) args.unshift(true);
        callback.apply(self,args);
      });
      cordovaFn.apply(cordovaFn,args);
    };
}

function isSmaller(a,b,success,error){
    if(a < b){
      success(b-a);
    } else {
      error();
    }
}
var isSmallerTest = toNodejsFn(isSmaller);

isSmallerTest(1,3,function(err,res){
  console.log('isSmaller(1,3): err === null',err === null);
  console.log('isSmaller(1,3): res === 2 (difference)',res === 2);
});

isSmallerTest(4,1,function(err,res){
  console.log('isSmaller(4,1): err !== null',err !== null);
});

toCallback.js

/**
 * convert a cordova-style function: fn(a,b,c,onSuccess,onError)
 * to a nodejs-style function: fn(a,b,c,callback)
 * 
 * where callback is fn(err,response) and err should be falsy (null,false,0,'') for success responses
 * 
 **/ 
module.exports = function toNodejsFn(cordovaFn,self){
    return function(){
      var args = Array.prototype.slice.call(arguments,0);
      var callback = args.splice(args.length-1,1)[0]; 
      args.push(function onSuccess(){
        var args = Array.prototype.slice.call(arguments, 0);
        args.unshift(null);
        callback.apply(self,args);
      });
      args.push(function onError(){
        var args = Array.prototype.slice.call(arguments, 0);
        // ensure the first argument is not-null
        if(args.length === 0 || !args[0]) args.unshift(true);
        callback.apply(self,args);
      });
      cordovaFn.apply(cordovaFn,args);
    };
}