jquery widget apply(this, arguments)

Question

Sometimes I see people using this to call function within a widget

this.myFunction.apply(this, arguments);

instead of this:

this.myFunction();

What's the .apply jQuery function?

somefunction.apply(thisobj, argsarray)

The above calls the function somefunction, setting this to thisobj within the function's scope, and passing in the arguments from argsarray as the arguments to the function.

But considering the case below, wouldn't it be the same whether calling the function directly or using .apply()? I've seen a few tutorials favor .apply() method instead, including the jQuery site itself. http://jqueryui.com/demos/widget/

Is this a widget 'standard' or is there something else that i'm missing?

_create: function() {
            var that = this;
            this.myButton = $( "<button>", {
                text: "My Button"
            })
            .appendTo( this.element )
            .bind("click", function() {
                // _bind would handle this check
                if (that.options.disabled) {
                    return;
                }
                that.displayMessage.apply(that, arguments);
                // Why not just call the following?
                // that.displayMessage();
            });
        },
displayMessage: function() {
        alert("Hey!");
    }

Answer 1

It is not jQuery, it's JavaScript. .apply() and .call() allow you to change what this means inside the function.