Question

function Activity() {

this.LoadFile = function (path, targetElement) {

    $.ajax({
        url: path,
        dataType: 'html',
        success: function (data) {
            targetElement.html(data);
        }

    });
};

this.LoadFile = function (path, targetElement, onSuccess) {

    $.ajax({
        url: path,
        dataType: 'html',
        success: function (data) {
            targetElement.html(data);
            onSuccess(data);
        }

    });
};

}

If i try to pass 2 arguments, i get onSuccess is not a function so i suppose this isnt working. Is it possible to use overloads in javascipt?

Answer 1

There’s no way of directly specifying overloaded methods as such in JS.

There are many workarounds.

In your case, you can define the function with 3 parameters:

function (path, targetElement, onSuccess)

and if the function is called with only 2 parameters, onSuccess will be undefined:

function (data) {
  targetElement.html(data);
  if (onSuccess) {
    onSuccess(data);
  }
}

_{You may want to look at jQuery.Callbacks for handling event callbacks, although your function could be rewritten using .load.}

---

For programmers coming from the Java/C# world of overloading learn the JavaScript way you can use a structure like this (not recommended, it’s simply an example for familiarity):

function foo() {
  var fns = {};
  fns[0] = function () {
    //no params
  };
  fns[1] = function () {
    //1 param
  };
  fns[2] = function () {
    //2 params
  };
  fns[arguments.length]();
}

to provide separate functions for each “overload”, however it’s not very flexible and symptomatic of a poorly planned function.

---

Oftentimes rather than using a large set of parameters, a single options parameter will be used to contain the available parameters:

function foo(options) {
  var settings = $.extend({}, foo.defaultSettings, options);
  //do stuff with settings
}
foo.defaultSettings = {
  bar: 'baz',
  fizz: 'buzz'
}