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JS Mobile Redirection

redirection_mobile.js is a utility script that covers a basic scenario for redirecting your website to a mobile verison through JavaScript.

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It also covers the scenario where a user wants to access the Desktop version of the site from a mobile device (sometimes the desktop version has more functionality).

The script handles tablets too, you can choose to redirect user to a mobile site or to a specific site for tablets (7'' or 10'').

Getting started

The script needs to be put in the desktop version of the site.

The script sniffs the User-Agent string and it decides if the redirection needs to happen.

If the user decides to view the 'desktop' version from a mobile site, the user is kept on that version for the whole session. (sessionStorage object has been used). There is a fallback for old browsers that don't support sessionStorage, and a cookie is used. The cookie expiries in one hour or you configure the expiry time.

To use this function, you need to import the "redirection_mobile.js" in your page and call the SA.redirection_mobile() function.

	<!doctype html>
			<script src="redirection-mobile.js"></script>


The function accepts few configurations:

  • mobile_prefix : prefix appended to the hostname. E.g. "m" to redirect to "". "m" is the default value if the property is not specified.

  • mobile_url : mobile url to use for the redirection (without the protocol), such as ""/example to redirect to "". If "mobile_prefix" exists too, "mobile_prefix" is ignored. Empty string is the default value.

  • mobile_scheme : url scheme (http/https) of the mobile site domain, such as "https" to redirect to "". The protocol of the current page is the default value.

  • redirection_param : parameter to pass in the querystring of the URL to avoid the redirection (the value must be equal to "false" to avoid redirection). Default value is "mobile_redirect". Eg: It is the name of the item in the sessionStorage (or cookie name) used to avoid mobile redirection.

  • cookie_hours : number of hours the cookie needs to exist after redirection to desktop site. "1" is the default value.

  • tablet_redirection : boolean value that enables/disables(default) the redirection for tablet such as iPad, Samsung Galaxy Tab, Kindle or Motorola Xoom. - Default:false. The value needs to be a string (so wrapped in double or single quotes). If 'tablet_host' parameter not specified, the user will be redirected to the same URL as for mobile devices.

  • tablet_host : hostname to use for the redirection in case user is using a tablet to access the site. Default value is ""

  • keep_path : boolean to determine if the destination url needs to keep the path from the original url. Default value is 'false'

  • keep_query : boolean to determine if the destination url needs to keep the querystring from the original url. Default value is 'false'

  • beforeredirection_callback : if specified, callback launched before the redirection happens. If a falsy value is returned from the callback the redirection doesn't happen.

  • append_referrer : boolean to determine if the document.referrer should be appended to the destination url. document.referrer will be URI encoded prior to appending. Default value is 'false'

  • append_referrer_key : if specified, the key used for the document.referrer. defaults to 'original_referrer'


If you want to redirect the user to "" from "":

	SA.redirection_mobile ({
		redirection_param : "mobile_redirection",
		mobile_prefix : "mobile",
		cookie_hours : "2" 

If you want to redirect the user to "":

	SA.redirection_mobile ({
		mobile_url : "",
		mobile_prefix : "https"

If you want to redirect the user to "" even when using an Ipad or a generic tablet:

	SA.redirection_mobile ({
		tablet_redirection : "true",
		mobile_url : "",
		mobile_prefix : "https"

If you want to avoid the redirection to happen from a callback, this is the invocation you need:

	SA.redirection_mobile ({
		beforeredirection_callback : (function(){alert("!"); return false;})

If you want to redirect the user to two different URLs depending on the device the user is using (mobile or tablet):

	SA.redirection_mobile ({
		mobile_url : "",
		tablet_host : "",

If the user accesses to "" and you want to redirect him to "":

	SA.redirection_mobile ({
		mobile_prefix : "mobile",
		keep_path : true,
		keep_query : true

What is 'redirection-mobile-self.js'?

Alternatively you can use "redirection_mobile_self.js", that is an anonyimous self-executing function using the default values for the different properties:

  • "mobile_prefix" : "m"
  • "redirection_param" : "mobile_redirect"
  • "cookie_hours" : 1
  • "mobile_url" : ""
  • "mobile_scheme" : protocol of the current page
  • "tablet_redirection" : "false"
  • "keep_path" : false
  • "keep_query" : false
  • "tablet_host" : ""
  • "beforeredirection_callback" : n/a

It doesn't need any configuration or any invocation, so you just need to drop "it "redirection_mobile_self.js" on your webserver and call the script from your HTML.

	<!doctype html>
			<script src="redirection_mobile_self.js"></script>
		<script src="/js/redirection_mobile_self.js"></script>

I also created 'redirection-mobile-testable.js' that is just a copy from "redirection_mobile.js", but it's using few arguments such as "document", "window", "navigator" for testing purpose.

Testing / Building the plugin

After getting node and npm, install grunt and grunt-jasmine-runner.

npm install grunt npm install grunt-jasmine-runner

You can run Jasmine specs through phantomjs with :

grunt jasmine

If you don't have phantomjs, please download it from here

You can run JSHint, Jasmine specs and minification tool simply launching: grunt


Copyright (c) 2011-2012 Sebastiano Armeli-Battana Licensed under the MIT license. (


JS to handle the redirection to the mobile version of your site




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