Skip to content


Folders and files

Last commit message
Last commit date

Latest commit


Repository files navigation


Doom is a Virtual Dom Library for Haxe. It is strictly typed (no Dynamics lurking around) and built to be easy to use.


Examples and demos with source code can be found here.


Make sure to have phantomjs installed.

Run the following commands from the root of the projects:

haxelib install hmm
hmm install
haxe build.hxml


A VNode (virtual node) is the basic rendering element in Doom. It can represent an element (like a DIV or an A), simple text or a Component.

Generating a VNode doesn't automatically render it. A VNode needs to be translated into browser DOM nodes. There are two ways to do that:

  • mount the VNode directly in the DOM
  • generate and return a VNode from a Component.render method.

To mount a VNode use Doom.render.mount():

import doom.html.Html.*;
import js.Browser.document as doc;

class Main {
  static function main()
      h1("I'm just a simple element"),

VNode Types

The following VNode types exist:

  • Element(name: String, attributes: Map<String, AttributeValue>, children: VNodes)
  • Comment(comment: String)
  • Raw(code: String)
  • Text(text: String)
  • Comp<Props, El>(comp: Component<Props, El>)

These can be generated using the homonymous methods on doom.core.VNode, doom.html.Html and/or doom.html.Svg (the last two are convenient aliases). The methods are el, comp, comment, raw and text. doom.html.Html also contains shortcut methods like div or input to generate equivalent nodes.


Most elements accept child elements, there are typed as VNodes which is an abstract on Array<VNode> with a few additional benefits (mostly implicit cast from common types).


Elements expect a Map<String, AttributeValue> to set the node attributes and properties. AttributeValue is a convenient abstract that simplifies assigning the right values to the attributes.

AttributeValue has 3 constructors:

  • BoolAttribute(b : Bool)
  • StringAttribute(s : String)
  • EventAttribute<T : Event>(f : T -> Void)

Here are the types that are implicitly converted to AttributeValue:

  • String for attributes like id or class
  • Map<String, Bool> mainly to be used with class. It is convenient to turn on and off class names:
  "class" => [
    "button" => true,
    "active" =>,
    style    => null != style
  • Bool used with attributes like disabled or checked
  • Void -> Void an event handler that doesn't care about information related to the even itself. click is the perfect example for it.
  • (T : Event) -> Void when you want an event handler and have full control on the Event object.
  • (T : Element) -> Void, the handler receives the original element that triggered the event.
  • String -> Void, the handler receives the text content of the element that triggered the event. The text content is retrieved in different ways according to the type of element (input, textarea, select, ...).
  • Bool -> Void, the handler receives a flag value from the checked attribute.
  • Int -> Void, works like String -> Void but tries to convert the value into an Int. If that cannot happen the handler is not invoked.
  • Float -> Void, same as Int -> Void but for floats.

Note: All event handlers except for (T : Event) -> Void will automatically call event.preventDefault().


A component is anything between a full UI application and a button. A component lives inside another component (as a VNode returned by the render method) or it can be mounted directly in the dom.

import doom.html.Component;
import doom.html.Html.*;
using thx.Objects;
import thx.Timer;

class Main {
  static function main() {
    var div = js.Browser.document.getElementById("main");
    Doom.browser.mount(new BannerComponent({
      messages : [ "Doom", "is", "Magic", "(but the good kind)" ],
      delay : 500,
      toDisplay : 0
    }), div);

class BannerComponent extends Component<BannerProps> {
  override function render() {
    Timer.delay(function() {
        toDisplay : (props.toDisplay + 1) % props.messages.length
    }, props.delay);
    return h1(props.messages[props.toDisplay]);

typedef BannerProps = {
  messages : Array<String>,
  delay : Int,
  toDisplay : Int

API documentation


  • TODO describe update
  • TODO describe state