Question

I have a function that looks like the function below. It takes an object called
link, calls getAdminParams and then uses the return values of that call to
change properties in the link object:

function checkParams(link: Link) {
    var rtn : IAdminParams = null,
        table = null;
    if (link.Action === "Create") {
        if (link.Params == null) {
            rtn = getAdminParams(link.Entity);
            if (rtn.Success) {
                link.Url = link.Href + rtn.Param;
                table = rtn.Table;
            } else {
                link.$Link.prop('disabled', false);
                return;
            }
        } else {
            link.Url = link.Href + link.Params;
            table = link.Entity;
        }
    } else {
        link.Url = link.Href;
    }
}

I am calling the function as below.

function adminDialog($link: JQuery) {
    var link = new Link($link);
    checkParams(link);
    doDialogAjax(link);
}

When I pass the value of link to the checkParams(link) will it be passed by
reference? In other words will the changes I make in the checkParams(link: Link)
function be available to the link object so they can be used in the doDialogAjax
function?

Answer 1

Yes, and no.

“When I pass the value of link to the checkParams(link) will it be
passed by reference?”

No.

“Will the changes I make in the checkParams(link: Link)
function be available to the link object so they can be used in the
doDialogAjax function?”

Yes.

The variable is not passed by reference. It’s passed by value, but the value is a reference.

If the variable was passed by reference, the function could change the variable. That doesn’t happen:

function change(obj) {
  // change the object
  obj.value = 42;
  // replace it with a new object
  obj = { value: 1 };
}

// create an object
var a = { value: 0 };

// create another variable, to use in the call to the function
var b = a;

change(b);

alert(a.value); // shows 42, as the function changes the object passed in
alert(b.value); // shows 42, not 1, as the variable b is not changed by the function

Demo: http://jsfiddle.net/sCJHu/

If the variable was passed by reference, b would be replaced by the new object create in the function, and b.value would be 1.