xnode

xnode

An extendable version of a DOM Node

Background

In traditional UI programming we are used to rely on extending components using object oriented programming. For example, we can create a window component, and then we extend it into a dialog component that has a number of buttons and an icon, and then we extend that into a message box that shows a message with an OK button. The HTML DOM has UI objects in a somewhat similar way, but unfortunatly these are not possible to extend. This is because they do not have constructors. When we want to create a Div object we do:

var element = document.createElement("div");

We don't do var element = new Div() or something like that which would be necessary in order to create a subclass that extends the Div DOM object.

Solution

This xnode hack, where xnode stands for extensible node, makes this possible. Using xnode, we can create elements using constructors instead of the document.createElement function. A hello world example would look like this:

var element = new xnode.Div();
element.innerHTML="Hello World";
document.body.appendChild(element);

Another example

This example create a dialog box and attaches it to the body:

function MyDialog(text) {
	xnode.Div.call(this);

	this.okButton = new xnode.Button();
	this.okButton.style.position = "absolute";
	this.okButton.style.bottom = "10px";
	this.okButton.style.left = "50%";
	this.okButton.style.width = "100px";
	this.okButton.style.marginLeft = "-50px";
	this.okButton.innerHTML = "Ok";
	this.appendChild(this.okButton);

	this.style.background = "#ff0000";
	this.style.width = "300px";
	this.style.height = "200px";
	this.style.position = "absolute";

	this.textElement = new xnode.Div();
	this.textElement.innerHTML = text;
	this.textElement.style.top = "10px";
	this.appendChild(this.textElement);

	this.okButton.on("click", function() {
		console.log("button click");
	});
}

inherits(MyDialog, xnode.Div);

var myDialog = new MyDialog("hello world");
document.body.appendChild(myDialog);