_off _on chaining not working.

In normal Jquery (not using UI) you can write the following code:

$("#test").off("click").on("click", function() {});

And have it work (source)

When I try to do this inside of a widget, like so:

this._off( $("li", this.sloshLeft), "dblclick")._on( $("li", this.sloshLeft), {

dblclick: function(event) {

}

});

I get the following error:

Uncaught TypeError: Cannot call method '_on' of undefined