In JS constructor accept an optional 'options' object

gistfile1.js

var layout = {
		Box: function(container, options) {
			$.extend(this, {
				vertical: false
			}, options);
};

// HOWEVER, for Eclipse to discover the fields of Box, this approach is
// needed

var layout = {
		Box: function(container, options) {
			this.vertical = true;
			this.gooClass = "gooey";
			$.extend(this, options);
			
			this.container = $(container);
		}
};