An asset manager based on custom elements


An tiny and easy to use web framework based on making custom HTML elements.

Creating Custom Elements

An elem is just a folder who's name is the tag name.

  • Files with extensions like widget.html.jadeare caught by the pre-processor and become widget.html.

  • When a <widget>appears on the page elem/loaderwill pull down all of the files in the widgetfolder.

  • If there is a widget.htmlthe element's inner html will be replaced with it.

  • If there is a widget.cssthe css will be added to the document.

  • If there is a widget.jsit will be treated like a node module. Here we can export a function that applies the behavior. This function is called for every instance of <widget>and passed an object containing all of the file contents of the folder.


module.exports = function widget() {

Giving the function two arguments makes it async, delaying rendering and loading child elements:

module.exports = function widget(done) {
  var self = this;

  $.get('/content.txt', function(text) {

Special Folders

  • */libis recursively pre-loaded before the element is applied. Put anything you want to require() in here so it is available when the element implementation.

  • */componentsare parsed as installed componentsand can be required globally.

  • */windowis recursively pre-loaded but executed without a module.exports.

    This is where you would put classic global libraries like jQuery.

    You could also component install component/jqueryand require('jquery'). But jQuery was always designed to extend window. Using it as a module breaks plugins.

    Everything in windowis run in top-down order of directory depth. So to make jQuery plugins run after jQuery, you can put them in a window/jquery-plugins/folder.

Express/Connect Middleware

var express = require('express');
var elem = require('elem');
var server = express();
var app = elem(__dirname+'/app');

var production = process.env.NODE_ENV == 'production';

server.use('/app', ui.loader({production: production}));

// Remove this route and include
// <script src="/app/loader.js">
// in a template if you don't want to use the bootloader.
app.get('*', ui.boot('/app'));


Package Management

Elem has has built-in supports for component.

$ npm install -g component
$ component install visionmedia/page.js


var page = require('page');

You can use libraries from bower or npm if you need to by symlinking:

bower install jquery
ln -s bower_components/jquery/dist/jquery.js frontend/window/

Client-side templating



var template = require('template');

module.exports = function(render) {
  var locals = {};
  render( template(locals) );

Client-side routing

component install page




<img src="reallybigimage.jpg">


var page = require('page');

module.exports = function(files, render) {
  // hello.html will not be injected
  // until the route is matched
  page('/hello', render);

Page Layouts

... can be deleted. Try making a dynamic <body> element instead.

- app
  - frontend
    - body
      - body.html.jade
      - body.css.styl
    - header
      - header.html.jade
      - header.css.styl
      - header.js
    - page
      - page.css.styl
      - page.js
    - window
      - jquery.js


The pre-processor keys off of sequential file extensions. e.g. any template.html.jade will envoke the .html.jade pre-processor and result in a static template.html build that is exposed to the element.

The standard pre-processors elem supports are:

  • .html.jade
  • .css.styl
  • .css.less

To add additional pre-processors, or override the built-in ones:

frontend.prep('.html.md', function(str, done){
  marked(str, done);

Note that if you override a built-in pre-processor, it will only apply to your own elements. Not installed ones.

By supporting these standard pre-processors element authors are able to use their templating language of choice without incuring a setup penalty. Since they are just pre-processors so there is no overhead.

If you think there is a pre-processor that should be standard make a pull request. The only requirement is that it be a well-known standard format.

No Headaches

Elem is built with the premise that your development and debugging workflow can never be impeded by the build process. In development mode, it actually enhances your workflow making it clear what code is responsible for what is happening on the page.

Development Mode:

  1. All files are requested independently.
  2. File names and line numbers are preserved.
  3. CSS is linked to the page, not injected.
  4. The final DOM is annotated with HTML comments that indicate how and where the markup was generated.
  5. Files are rebuilt on request, and only when they have changed.


elem(1)is provided as a convenience for developing isolated elements. It is not meant to be a real web server.

$ npm install -g elem
Usage: elem [options] <file ...>


  index [options]        build index


  -h, --help     output usage information
  -V, --version  output the version number
elem create widget
elem run widget







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