adding callback to function - always

Question

I found myself using a weird way to add callback functions to my functions and I was wondering if there is a more generic way to add callbacks to functions, best case I would have a situation where all of my functions check the last given param for being a function and if so use it as a callback.

This is how I did it in the past:

var myFunc = function( obj ) {

  if ( arguments.length > 0 ) {
    if ( _.util.typeofObj( arguments[arguments.length-1] ) === Function ) {
      var callback = arguments[arguments.length-1];
    }
  }

  // some code ...

  if ( callback !== undefined ) {
    callback();
  }

};

var foo = myFunc( myObj, function(){
  alert( 'Callback!' );
});

Any suggestions?

Answer 1

I prefer a formal parameter:

var myFunc = function(obj, callback) {
   ...
}

This way it makes it obvious that there is a callback. You also don't have to mess around with the arguments object; you can just check to see if callback is undefined, and then check to see if it is of the appropriate type (Function).