git @ Cat's Eye Technologies DAM / master

Tree @master (Download .tar.gz)


You've tried the Document Object Model, now try the Document Awesome Model!

(FIXME TODO put twee picture of cartoon beaver mascot here)

What is this

DAM is a tiny library for creating bits of an HTML5 document. (I'd say "for creating user interfaces" but that may be overstating it a tad.) It's written in ES5 Javascript, so it can be used directly by most modern web browsers, or it can included as part of a modern frontend build process. Even uncompressed it's only about 1K in size, and it ships with a minified version which includes a "standard widget library" that is still less than 4K.

The current version of DAM is 0.2.

Basic usage

The simplest way to use DAM is to simply load it directly on a web page, and use it like so:

<script src="dist/dam-0.2.js"></script>
  var div=DAM.maker('div'), p=DAM.maker('p'), span=DAM.maker('span'), button=DAM.maker('button');
  var d = div(
      "Hello, ", span("world"), "."
    button({ onclick: function(e) { alert(e); } }, "Alert!")

DAM.maker is a function that takes a tag string and returns a function that creates and returns a DOM Element with that tag.

The returned function also takes any number of arguments. Each argument influences the DOM Element that is created:

  • A string argument will create a child text node inside the Element.
  • A DOM Element argument will insert that Element as a child of the Element.
  • A null or undefined argument will be ignored.
  • A plain Javascript object argument will configure the created Element; each key in the object sets one attribute of the created Element. In this case, some keys and values are treated specially:
    • Keys must always be strings.
    • A key that starts with on will set up an event handler.
    • A null value will unset the attribute.


If you have a pattern of elements that you create over and over, you can package that up in a function that creates those elements. DAM calls this package a widget, and the function that creates it a widget maker. The names of DAM widget makers usually begin with make.

A simple example based on the code above:

<script src="dist/dam-0.2.js"></script>
  var div=DAM.maker('div'), p=DAM.maker('p'), span=DAM.maker('span'), button=DAM.maker('button');
  function makeGreeting(config) {
    return div(
        "Hello, ", span(config.who), "."
      button({ onclick: function(e) { alert(e); } }, "Alert!")
  var greets = div(
    makeGreeting({ who: "world" }),
    makeGreeting({ who: "Earthlings" }),
    makeGreeting({ who: "there" })

By convention, the first argument of a widget maker is a configuration object which configures the widget; it is completely widget-specific.

If the widget supports it, the remaining arguments will then be applied to the widget, in the same manner as the arguments passed to the function returned by DAM.maker are applied to the new element it creates.

If the widget is a "container widget" then it should definitely support this, as a means of letting the caller add children to the widget.

"Applied to the widget" might mean "applied to one of the elements of the widget", if the widget is composed of several elements.

Supplied widget library

dam-widgets.js defines a number of widgets built on top of DAM. Having these widgets readily available so that I could re-use them across my projects is one of the main reasons I bothered to put this DAM thing together. All the same, you can just treat these as examples or starting points for new widgets.

Unlike the other files, dam-widgets.js is written in ES6. If you want to use it in an ES6 project, you can, for example,

import DAM from "./dam.js"
import { makeCheckbox, makePanel } from "./dam-widgets.js"

However, you're not required to do this. If you just want an ES5 file that you can load in a web page, DAM ships with dist/dam-plus-widgets-0.2.min.js for this purpose. Just:

<script src="dist/dam-plus-widgets-0.2.min.js"></script>

and then you will have DAM as well as all the standard widget makers (nested under DAM) at your fingertips.

Distribution files

Note that the package.json supplied in this repository builds the files in dist/ from the source files in src/ using Browserify and Babel. It builds minified versions too. But this is just a convenience. The file src/dam.js is ES5 JavaScript and can be loaded directly in a web page and it will work fine in most modern browsers. Similarly, dam-plus-widgets-0.2.js could, in a pinch, be constructed by hand from the files src/dam.js and src/dam-widgets.js.

You can also import the DAM source files as ES6 modules in your own frontend build process. See the demo/es6build/ directory of this repository for an example of this.

Advanced widget creation

The function returned by DAM.maker is simply DAM.makeElem with some arguments pre-set and transformed. The tag passed to DAM.maker is passed as the first argument to DAM.makeElem, and the argument list received by the function returned by DAM.maker is passed as the second argument to DAM.makeElem, as a plain Javascript array.

But DAM.makeElem can be called directly, and calling it directly allows more explicit access to its arguments. Thus it is often called directly in widget makers.

Some projects DAM is used in

You can think of DAM as something like hyperscript except:

  • It has hyperscript-helpers built-in (sort of)
  • It has no dependencies
  • It doesn't try to parse what you want (you have spell out what you want)
  • It doesn't make as many promises about what it can do
  • It doesn't have an ecosystem, only a convention for widget makers
  • It's in the public domain

I was only peripherally aware of hyperscript when I wrote this; any similarities are probably because certain solutions (such as setting attributes from an object) are "obvious". (But I saw no need for e.g. htmlFor when you can just put 'for' in single quotes...)