/redirection_mobile.js

/*!

* JS Redirection Mobile

*

* Developed by

* Sebastiano Armeli-Battana (@sebarmeli) - http://www.sebastianoarmelibattana.com

* Dual licensed under the MIT or GPL Version 3 licenses.

*/

/*

	Copyright (c) 2011 Sebastiano Armeli-Battana (http://www.sebastianoarmelibattana.com)



	This program is free software: you can redistribute it and/or modify

	it under the terms of the GNU General Public License as published by

	the Free Software Foundation, either version 3 of the License, or

	(at your option) any later version.



	This program is distributed in the hope that it will be useful,

	but WITHOUT ANY WARRANTY; without even the implied warranty of

	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

	GNU General Public License for more details.



	You should have received a copy of the GNU General Public License

	along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/



/*

* This script will cover a basic scenario of full JS mobile redirection.

* The user will be redirected to the mobile version of the site (home page)

* if it's trying to access the site from a mobile device. This check is

* mainly done checking the User-Agent string. 

* The mobile URL will be obtained appending a prefix (default is "m") to 

* the hostname of the current URL. It's used a naked domain to avoid conflict with

* www.

* 

* In some cases the user needs to be redirected to the Desktop version of the site 

* from a mobile device. This happens when the user clicks on a link such as "Go to full site"

* or when there is a specific parameter in the querystring.

*

* In that case a new key/value in sessionStorage (for modern browsers) 

* will be set and until the user doesn't close browser window or tab it will access

* to the desktop version from a mobile device. There is a fallback for old browsers that

* don't support sessionStorage, and it will use a cookie. The cookie will expiry in one hour 

* (default value) or you configure the expiry time.

* 

* To use this function, you need to call it as SA.redirection_mobile(config);

* E.g. SA.redirection_mobile ({redirection_paramName : "modile_redirect", mobile_prefix : "mobile", cookie_hours : "2" })

* or

* E.g. SA.redirection_mobile ({mobile_url : "mobile.whatever.com/example", mobile_sheme : "https" })

* or

* E.g. SA.redirection_mobile ({mobile_prefix : "mobile", mobile_scheme : "https"})

* or

* E.g. SA.redirection_mobile ({mobile_prefix : "mobile", mobile_scheme : "https", redirection_paramName : "modile_redirect"})

* or

* E.g. SA.redirection_mobile ({mobile_url : "mobile.whatever.com/example", tablet_redirection : "true"})

* or

* E.g. SA.redirection_mobile ({{mobile_url : "mobile.whatever.com/example", beforeredirection_callback : (function(){alert('2')}) }})

*

*

* @link http://github.com/sebarmeli/JS-Redirection-Mobile-Site/

* @author Sebastiano Armeli-Battana

* @version 0.8.6

* @date 02/04/2011 

* 

*/

	

/*globals window,document, navigator, SA */

if (!window.SA) {window.SA = {};}



/*

* @param configuration object containing three properties:

*			- mobile_prefix : prefix appended to the hostname (such as "m" to redirect to "m.domain.com")

*			- mobile_url : mobile url to use for the redirection (such as "whatever.com" to redirect to "whatever.com" )

*			- mobile_scheme : url scheme (http/https) of the mobile site domain

*			- cookie_hours : number of hours the cookie needs to exist after redirection to desktop site

*			- redirection_paramName : parameter to pass in the querystring of the URL to avoid the redirection (the value must be equal to "false").

*				It's also the name of the item in the localStorage (or cookie name) to avoid mobile

*				redirection. Default value is "mobile_redirect". Eg: http://domain.com?mobile_redirect=false

*			- tablet_redirection : boolean value that enables/disables(default) the redirection for tablet such as iPad, Samsung Galaxy Tab, Kindle or Motorola Xoom. - Default:false

*			- beforeredirection_callback : callback launched before the redirection happens

*/

SA.redirection_mobile = function(configuration) {



	// Helper function for adding time to the current date

	var addTimeToDate = function(msec) {



		// Get the current date

		var exdate = new Date();



		// Add time to the date

		exdate.setTime(exdate.getTime() + msec);



		//Return the new Date

		return exdate;



	};



	// Helper function for getting a value from a parameter in the querystring

	var getQueryValue = function(param) {



		if (!param) {

			return;

		}



		var querystring = document.location.search,

			queryStringArray = querystring && querystring.substring(1).split("&"),

			i = 0,

			length = queryStringArray.length;



		for (; i < length; i++) {

			var token = queryStringArray[i],

				firstPart = token && token.substring(0, token.indexOf("="));

			if (firstPart === param ) {

				return token.substring(token.indexOf("=") + 1, token.length);

			}

		}



	};

				

	// Retrieve the User Agent of the browser

	var agent = navigator.userAgent.toLowerCase(),

	

		// Constants

		FALSE = "false",

		TRUE = "true",



		// configuration object

		config = configuration || {},

	

		// parameter to pass in the URL to avoid the redirection

		redirection_param = config.redirection_paramName || "mobile_redirect",

		

		// prefix appended to the hostname

		mobile_prefix = config.mobile_prefix || "m",

		

		// new url for the mobile site domain 

		mobile_url = config.mobile_url,

		

		// protocol for the mobile site domain 

		mobile_protocol = config.mobile_scheme ?

			config.mobile_scheme + ":" :

				document.location.protocol,

		

		// URL host of incoming request

		host = document.location.host,



		// value for the parameter passed in the URL to avoid the redirection

		queryValue = getQueryValue(redirection_param),



		// Compose the mobile hostname considering "mobile_url" or "mobile_prefix" + hostname

		mobile_host = mobile_url ||

			(mobile_prefix + "." + 

				(!!host.match(/^www\./i) ?

					host.substring(4) : 

						host)),



		// Expiry hours for cookie

		cookie_hours = config.cookie_hours || 1,



		// Check if the UA is a mobile one (iphone, ipod, android, blackberry)

		isUAMobile =!!(agent.match(/(iPhone|iPod|blackberry|android 0.5|htc|lg|midp|mmp|mobile|nokia|opera mini|palm|pocket|psp|sgh|smartphone|symbian|treo mini|Playstation Portable|SonyEricsson|Samsung|MobileExplorer|PalmSource|Benq|Windows Phone|Windows Mobile|IEMobile|Windows CE|Nintendo Wii)/i));





	// Check if the referrer was a mobile page (probably the user clicked "Go to full site") or in the 

	// querystring there is a parameter to avoid the redirection such as "?mobile_redirect=false"

	// (in that case we need to set a variable in the sessionStorage or in the cookie)

	if (document.referrer.indexOf(mobile_host) >= 0 || queryValue === FALSE ) {



		if (window.sessionStorage) {

			window.sessionStorage.setItem(redirection_param, FALSE);

		} else {

			document.cookie = redirection_param + "=" + FALSE + ";expires="+

				addTimeToDate(3600*1000*cookie_hours).toUTCString();

		}

	}



	// Check if the sessionStorage contain the parameter

	var isSessionStorage = (window.sessionStorage) ? 

			(window.sessionStorage.getItem(redirection_param) === FALSE) :

				false,



		// Check if the Cookie has been set up

		isCookieSet = document.cookie ? 

			(document.cookie.indexOf(redirection_param) >= 0) :

				false;

	

	// Check if the device is a Tablet such as iPad, Samsung Tab, Motorola Xoom or Amazon Kindle

	if (!!(agent.match(/(iPad|SCH-I800|xoom|kindle)/i))) {



		// Check if the redirection needs to happen for iPad

		isUAMobile = (config.tablet_redirection === TRUE) ? true : false;



	}



	// Check that User Agent is mobile, cookie is not set or value in the sessionStorage not present

	if (isUAMobile && !(isCookieSet || isSessionStorage)) {



		// Callback call

		if (config.beforeredirection_callback) {

			if (!config.beforeredirection_callback.call(this)) {

				return;

			}

		}

		

		document.location.href = mobile_protocol + "//" + mobile_host;

	} 

};