Creating A Web App

Creating a app goes through these phases

1. creating a App Manifest

1. serve the manifest with web app

1. Appify the code

1. Validate the markup

1. Publlish the app

Manifest

{
  "name": "My App",
  "description": "My elevator pitch goes here",
  "launch_path": "/index.html",
  "icons": {
    "512": "/img/icon-512.png",
    "128": "/img/icon-128.png"
  },
  "developer": {
    "name": "Your name or organization",
    "url": "http://your-homepage-here.org"
  },
  "default_locale": "en",
  "chrome": { "navigation": true }
}

https://developer.mozilla.org/en-US/Apps/Build/Manifest

Explanation for each steps

step 1 literally signifies the Manifest Sample part where you provide details about the

 Developers name and the details about the App and it has a extension called as .webapp

Here are for API

Telephone

var tel = navigator.mozsms //creating object

Sms

sms.send('12345677','Hello') //Sending to system

sms.OnReceived = function(event) // Reply from the Telephone

Console.log(event.message)

step 2 Serve the manifest with the app, it more like the coding path where you use HTML CSS and JS 

Step 3 it says that the app must fit into all type of the screen thereby giving the app look 

Step 4 Validating the markup in this case it is HTML 

Step 5 Finally pushing the app into the market place.

  The app should consists of 

index.html

Ui.css

function.js

Manifest.webapp

The app can be uploaded as website else it can be zipped

The Os first looks into the manifest then it goes through the given path

For more details check out the firefox developers Blog