Building a Todo app for Firefox OS, part 1

This is the first part out of two in a tutorial series where we will build a Todo app for Firefox OS from scratch. I assume you have some understanding of HTML5, CSS3, JavaScript, jQuery/Zepto, and Backbone.js. In this part we will handcraft a properly structured and semantic UI of a Todo app using best practices for designing UIs for mobile.

The source for the Todo app is available on GitHub.

Setting Up the Environment

We will use volo as our package manager and build tool.

Step 1

First you need to install Node.js because volo depends on it. Windows and Mac users can download it from here. But for Linux users, I recommend you use the package manager: instructions for installation using package manager on different distros.

Step 2

Install volo using the following command.

npm install -g volo

Make sure you use `sudo` before above command in *nix environment.

Step 3

Create a blank project fos-todo-app using `volo create` command.

volo create fos-todo-app

This will create a folder fos-todo-app and copy required volo project files from GitHub.

Remember we will work only with the files in fos-todo-app/www directory. If you have never worked with volo before, [Streamline your Process with Volo]( is a recommended read.

Step 4

Make sure you have the latest stable version of Firefox installed. Then [install the Firefox OS simulator add-on]( At the end of this article we will test UI of our app in this simulator.

Step 5

Get the [MozTT font]( and install it. MozTT is the font used in Firefox OS. It’s an optional step but it’s better to install this font on your system so you can get consistent look and feel in the Firefox OS Simulator and the real phone.

Todo View

The first UI that we will build will show a title in the header, Add/Delete buttons in the footer and a todo list. This view will be used for viewing, editing, mark as complete, and deleting tasks.

Todo View - Firefox OS

Add role="application" attribute to the `body` element and write following HTML for the Todo View.


Each view is assigned a role="region". Within the view, you can have header, footer and any container element having the view-content class which will contain the contents of the view.

In the above view’s content, we have ul[role=list] which contains tasks entered by user. For testing purposes, I added two dummy tasks so you can understand each list item’s (`li[role=listitem]`) structure. Within each list item we have a label element containing a <input type="checkbox"> and a span element containing the text of task. The second element in the list item contains a <input type="text"> element which is initially hidden using attribute aria-hidden="true". Finally the third element is .btn.edit (edit button).

Note: Of course it’s not magic. We will write CSS for all these attributes. Check out ARIA and Progressive Enhancement if you are new to WAI-ARIA.

The purpose of placing the label in the list item is to display each task’s text and input[type=text] (which is initially hidden) will be used to edit that text. Any task can enter edit mode when user tap on .btn.edit (edit button). Similarly, tasks are “marked as completed” when user tap on label.

In the footer we have menu[role=toolbar] containing Add/Delete buttons. Later using CSS for these buttons, we will display a svg icon in background and hide an inner span in it.

Add View

The second and final view in our app will be used to add tasks to the todo list.

Add View

In this view we have a textbox for entering a task’s text, and a insert contact link will be used to add the contact number using Web Activities. Here’s the HTML for Add View.

[+] Todo

Note that the contents in section.view-content is wrapped using div.wrapper so we can limit its max-width and right align menu.options.

Second thing to note here is the aria-owns attribute on form element. This attribute relates to the form with btn-add-done.

Element Styles

Let’s write the CSS for the HTML elements. An explanation is given in comments above each selector.

/* Stretch vertically */
html, body { height: 100%; }

body {
  background: radial-gradient(ellipse at center, rgba(231,76,60,1) 0%,rgba(192,57,43,1) 100%);
  color: #fff;
  font-family: MozTT, sans-serif;

  /* Reset base size */
  font-size: 16px;

  /* Set font size relative to base size */
  /* Check this article on rem usage */
  font-size: 1.4rem;

  font-weight: 300;

  /* Remove spacing */
  margin: 0;

h1, h2, h3, h4, h5, h6 { font-weight: 300; }

h1 { font-size: 3rem; }

a {
  color: #FFA49E;
  text-decoration: none;
  text-shadow: 0px 1px 1px rgba(0,0,0,.3);
a:hover { color: #fff; }

input, button, select, textarea {
  border-radius: 0;
  box-shadow: none;
input[type=text], textarea, select {
  border: none;
  font-family: MozTT, sans-serif;
  font-size: 1.3rem;
  font-weight: 300;
  padding: .7rem .8rem;

View Specific Styles

#view-todos > .view-content {
  margin-left: 0;
  margin-right: 0;

#view-add > .view-content {
  margin-top: 2rem;
#view-add > .view-content > .wrapper {
  overflow: hidden;
  margin: 0 auto;
  max-width: 800px;
  width: 100%;
#view-add input[name=task] {
  width: 100%;
#view-add .options {
  margin: 0 0 .5rem 0;
  text-align: right;
#view-add .options [role=listitem] {
  margin: .5rem 0;
#view-add .options a {
  padding: .4rem;

Module Styles

View Module

/* All views have region role so selecting them with attribute selector  */
[role=region] {
  background: radial-gradient(ellipse at center, rgba(231,76,60,1) 0%,rgba(192,57,43,1) 100%);

  /* Stretch both vertically/horizontally */
  top: 0; right: 0; bottom: 0; left: 0;

  position: fixed;
  overflow-x: hidden;
[role=region] > header {
  margin: .5rem 0 1rem 0;
  text-align: center;
[role=region] > header > h1 {
  margin: 0;
  text-shadow: 0px 1px 1px rgba(0,0,0,.4);
[role=region] > .view-content {
  margin: 0 1rem 4rem 1rem;
[role=region] > footer {
  background: rgba(0,0,0,.2);
  right: 0; bottom: 0; left: 0;
  position: fixed;
  text-align: center;
[role=region] > footer > menu[role=toolbar] {
  margin: 0;
  padding: 0;

Button Module

.btn {
  border: none;
  width: 3.5rem;
  height: 3.5rem;
.btn > span {
  display: none;
.btn:disabled {
  opacity: .2;
.btn.done {
  background: url(../img/check.svg) no-repeat center center;
.btn.add {
  background: url(../img/add.svg) no-repeat center center;
.btn.del {
  background: url(../img/del.svg) no-repeat center center;
.btn.edit {
  background: url(../img/edit.svg) no-repeat center center;
.btn:hover {
  background-color: rgba(255,255,255,.1);

Todo List Module

.todo-list > li {
  border-bottom: 1px solid rgba(255,255,255,.1);
  position: relative;
.todo-list > li > .btn {
  top: 0; right: 0;
  position: absolute;
  height: 3.9rem;
.todo-list label {
  border-bottom: 1px solid rgba(0, 0, 0, 0.1);
  display: block;
  padding: 1rem 2.8rem 1rem 1rem;
.todo-list > li:last-child,
.todo-list > li:last-child > label {
  border-bottom: none;
.todo-list label > span {
  transition: all .5s;

  This selector is interesting. It creates a line-through and
  decrease opacity of text in span when checkbox is checked
.todo-list input[type=checkbox]:checked + span {
  text-decoration: line-through;
  opacity: .4;

.todo-list > li > input[type=text] {
  margin: .4rem;
  /* removing input padding and margin from 100% */
  width: calc(100% - 2.3rem);

Utility Styles

.reset-list {
  list-style: none;
  margin: 0;
  padding: 0;
[aria-hidden=true] {
  display: none !important;


Following are a few animation effects that we will use to animate our views. Although we will use Zepto.js which on run-time generates CSS3 animations using JavaScript, I prefer to write my own animations using CSS3 and make use of it by applying/removing CSS classes on DOM elements.

Zepto is a minimalist JavaScript library for modern browsers with a largely jQuery-compatible API. If you use jQuery, you already know how to use Zepto. ‐

Check out the How to use CSS Animations tutorial for understanding CSS3 Animations better.

.slide-up-in {
  animation-name: slide-up-in;
  animation-duration: .6s;
  transform: translateY(0%);
  opacity: 1;
@keyframes slide-up-in {
  0% { transform: translateY(30%); opacity: 0; }
  100% { transform: translateY(0%); opacity: 1; }

.slide-down-out {
  animation-name: slide-down-out;
  animation-duration: .6s;
  transform: translateY(30%);
  opacity: 0;
@keyframes slide-down-out {
  0% { transform: translateY(0%); opacity: 1; }
  100% { transform: translateY(30%); opacity: 0; }

.slide-right-in {
  animation-name: slide-right-in;
  animation-duration: .6s;
  transform: translateX(0%);
@keyframes slide-right-in {
  0% { transform: translateX(-100%); }
  100% { transform: translateX(0%); }

.slide-left-out {
  animation-name: slide-left-out;
  animation-duration: .6s;
  transform: translateX(-100%);
@keyframes slide-left-out {
  0% { transform: translateX(0%); }
  100% { transform: translateX(-100%); }

Testing in Firefox OS Simulator

Firefox OS Simulator

You can pretty easily test the UI we have developed using the Firefox OS Simulator. All you need is a manifest.webapp file in root directory (fos-todo-app/www). Add the following json in it.

  "version": "0.1",
  "name": "Todos",
  "description": "Awesome todo app by iFadey",
  "launch_path": "/index.html",
  "icons": {
    "16": "/img/icons/icon-16.png",
    "48": "/img/icons/icon-48.png",
    "128": "/img/icons/icon-128.png"
  "developer": {
    "name": "Fawad Hassan",
    "url": ""
  "installs_allowed_from": ["*"],
  "appcache_path": "/cache.manifest",
  "default_locale": "en"

Currently I haven’t added an app icon but don’t worry about it. Firefox OS adds a default app icon if it doesn’t find one mentioned in the manifest file. Now open the simulator tab from Tools > Web Developer > Firefox OS Simulator. Then click Add Directory button and select the manifest file from our app directory. This will add our app in the simulator.

End of part 1

Now you have gotten started with the Todo app and have gotten going with a few easy steps. In next part we will add life in our app using JavaScript (Backbone/Zepto). We will create Todo model, collection, and views and for the sake of simplicity, we will only store our todo collection in IndexedDB. We will also make use of Web Activities to inject contact number in text of todo task.

About Fawad Hassan

I am a JavaScripter and I love working on single page apps, Firefox OS, PhoneGap based mobile apps, and Node.js/Express.js backend. Currently I am working for PLUMgrid (SDN related startup) and I am working on HTML5 based GUI of Network Operating System. Other than that I am Mozillian and in my free time I promote Mozilla products.

More articles by Fawad Hassan…

About Robert Nyman [Editor emeritus]

Technical Evangelist & Editor of Mozilla Hacks. Gives talks & blogs about HTML5, JavaScript & the Open Web. Robert is a strong believer in HTML5 and the Open Web and has been working since 1999 with Front End development for the web - in Sweden and in New York City. He regularly also blogs at and loves to travel and meet people.

More articles by Robert Nyman [Editor emeritus]…


  1. jay

    Its funny that you have to depend on node.js when Mozilla have their own Javascript engines (rhino, spidermonkey)

    June 4th, 2013 at 11:01

    1. Andre Garzia


      the reason for using nodejs is beyond the fact that it is a javascript engine. NodeJS has a vibrant ecosystem of libraries and tools ( that can make you more productive. The volo package manager used in this tutorial is built on top of nodejs/npm and thats why it is used in this article. If rhino or a standalone spidermonkey supported the npm libraries, then you could use that. Its not that Mozilla javascript engines don’t meet the need of executing js like node, its just that node has a lot of libraries and a very good ecosystem and Mozilla embraced that in some demos and tools. Node is great and so is spidermonkey.

      June 4th, 2013 at 15:34

    2. Fawad Hassan

      Looks like there is confusion. I didn’t used Node.js in this tutorial nor I will use in future part. The only thing I used that require node.js is volo which is also a tool from Mozilla’s employee (James Burke). He’s the same guy who developed require.js :)

      June 5th, 2013 at 01:06

  2. Tojo Chacko

    Wow.. Looking forward to Part 2 :)

    June 4th, 2013 at 21:20

    1. Robert Nyman [Editor]

      Glad you liked it!

      June 5th, 2013 at 01:47

  3. Alexandre Girard

    Great beginning, looking forward to Part 2!

    Thanks for the external tools and font!

    June 5th, 2013 at 04:00

    1. Fawad Hassan

      Your welcome :)

      June 5th, 2013 at 04:08

  4. Raphael Martinez

    This is pretty awesome. Thanks for the extensive tutorial/demo. Can’t wait for part 2 :)

    June 5th, 2013 at 15:14

  5. AmirolAhmad


    I build my own Firefox OS in .php but when run in Firefox OS Simulator, it crush. Can it just running for html only?

    Please check mine:

    June 9th, 2013 at 10:27

    1. Fawad Hassan

      I tested this by creating an HTML file with php extension and set my launch_path in manifest.webapp file accordingly. It doesn’t work. Firefox OS simulator gives “Save As…” option to download that php file instead of executing HTML code in it.

      June 10th, 2013 at 01:42

    2. Robert Nyman [Editor]

      It depends on how you set it up. If you have a local or remote web server set up running PHP, it will run that within your app just like any web site. It won’t run PHP directly in itself, since the platform/app environment just supports HTML locally.

      Basically, like this blog. You could put in and it would run this web site within an app, but you couldn’t take the source code from here and run it directly.

      However, IF you can’t point to a URL on a server with a .php ending in the Firefox OS Simulator, then that’s a bug: please file that as an issue.

      June 10th, 2013 at 02:06

      1. Fawad Hassan

        Yes I understand that php code won’t run directly in Firefox OS. I added plain HTML in the php file tried that. I think its a bug. I will file it.

        June 13th, 2013 at 01:10

  6. Work

    You did not explain where to put the code.

    I put the html code into www/index.html and the CSS code into
    www/css/foo.css and added a in the section of index.html

    But Ionly see the second screen “Todo”not the first “Todos”

    I assume that in part 2 you are planning to put all this together? Perhaps some javascript to control the visibility of the sections?

    Commenting out the view-add section I see that checking the checkbox causes that item to have line through it. How was that achieved?


    June 27th, 2013 at 16:02

    1. Fawad Hassan

      All CSS goes in single file. If you have confusion with anything, you compare it with the source on GitHub. Here’s the app.css file:

      Line through thing is done purely using CSS. Check CSS for “Todo List Module”:

      This selector is interesting. It creates a line-through and
      decrease opacity of text in span when checkbox is checked
      .todo-list input[type=checkbox]:checked + span {
      text-decoration: line-through;
      opacity: .4;

      Yes Part 2 is all about JavaScript.

      June 27th, 2013 at 22:45

  7. Worik

    That would be a misspelt name on my part!


    June 27th, 2013 at 16:03

  8. uokesita

    Where is the second part? :(

    June 28th, 2013 at 22:03

    1. Fawad Hassan

      Part 2 was completed last week but delayed because there were too many articles in queue which needs to get published. So part 2 will get published on 2nd July (Tuesday).

      June 29th, 2013 at 02:59

    2. Robert Nyman [Editor]

      It will be published here tomorrow, July 2nd.

      July 1st, 2013 at 03:02

Comments are closed for this article.