express-device

Browser detection library, built on top of express

express-device

why express-device?

I'm really into node.js and lately I've been playing a lot with it. One of the steps I wanted to take in my learning path was to build a node.js module and published it to npm.

Then I had an idea: why not develop a server side library to mimic the behaviour that Twitter's Bootstrap has in order to identify where a browser is running on a desktop, tablet or phone. This is great for a responsive design, but on the server side.

how it came to be?

First I started to search how I could parse the user-agent string and how to differentiate tablets from smartphones. I found a couple good references, such as:

http://www.useragentstring.com/pages/useragentstring.php
http://detectmobilebrowsers.com/
http://www.quirksmode.org/js/detect.html
http://googlewebmastercentral.blogspot.pt/2011/03/mo-better-to-also-detect-mobile-user.html
http://www.htmlgoodies.com/beyond/webmaster/toolbox/article.php/3888106/How-Can-I-Detect-the-iPhone--iPads-User-Agent.htm
http://windowsteamblog.com/windows_phone/b/wpdev/archive/2011/08/29/introducing-the-ie9-on-windows-phone-mango-user-agent-string.aspx

But then I came across with Brett Jankord's blog. He developed Categorizr which is what I was trying to do for node.js but for PHP. He has the code hosted at Github. So, express-device parsing methods (to extract device type) are based on Categorizr. Also I've used all of his user-agent strings compilation to build my unit tests.

how to use it?

To install it you only need to do:

$ npm install express-device

Case you're using express 2.x.x you should install version 0.1.2:

$ npm install express-device@0.1.2

express-device is built on top of express framework. Here's an example on how to configure express to use it:

app.configure(function(){
    app.set('view engine', 'ejs');
    app.set('view options', { layout: false });
    app.set('views', __dirname + '/views');
 
    app.use(express.bodyParser());
    app.use(device.capture());
});

By doing this you're enabling the request object to have a property called device, which have the following properties:

Name	Field Type	Description	Possible Values
type	string	It gets the device type for the current request	desktop, tv, tablet, phone or bot

Since version 0.3.4 you can now override some options when calling device.capture(). It accepts an object with only the config options you which to override (go here for some examples). The ones you don't override it will use the default values. Here's the list with the available config options:

Name	Field Type	Description	Possible Values
emptyUserAgentDeviceType	string	Device type to be returned whenever the request has an empty user-agent. Defaults to phone.	desktop, tv, tablet, phone or bot
unknownUserAgentDeviceType	string	Device type to be returned whenever the request user-agent is unknown. Defaults to desktop.	desktop, tv, tablet, phone or bot
botUserAgentDeviceType	string	Device type to be returned whenever the request user-agent belongs to a bot. Defaults to bot.	desktop, tv, tablet, phone or bot

express-device can also add some variables to the response locals property that will help you to build a responsive design:

is_desktop	It returns true in case the device type is "desktop"; false otherwise
is_phone	It returns true in case the device type is "phone"; false otherwise
is_tablet	It returns true in case the device type is "tablet"; false otherwise
is_mobile	It returns true in case the device type is "phone" or "tablet"; false otherwise
is_tv	It returns true in case the device type is "tv"; false otherwise
is_bot	It returns true in case the device type is "bot"; false otherwise
device_type	It returns the device type string parsed from the request

In order to enable this method you have to pass the app reference to **device.enableDeviceHelpers(app)**, just before **app.use(app.router)**.

Here's an example on how to use them (using EJS view engine):

<html>
<head>
    <title><%= title %></title>
</head>
<body>
    <h1>Hello World!</h1>
    <% if (is_desktop) { %>
    <p>You're using a desktop</p>
    <% } %>
    <% if (is_phone) { %>
    <p>You're using a phone</p>
    <% } %>
    <% if (is_tablet) { %>
    <p>You're using a tablet</p>
    <% } %>
    <% if (is_tv) { %>
    <p>You're using a tablet</p>
    <% } %>
    <% if (is_bot) { %>
    <p>You're using a tablet</p>
    <% } %>
</body>
</html>

You can check a full working example here.

In version 0.3.0 a cool feature was added: the ability to route to a specific view\layout based on the device type (you must pass the app reference to .device.enableViewRouting(app) to set it up). Consider the code below:

.
|-- views
    |-- phone
    |    |-- layout.ejs
    |    `-- index.ejs
    |-- layout.ejs
    `-- index.ejs

And this code:

app.configure(function(){
    app.set('view engine', 'ejs');
    app.set('view options', { layout: true });
    app.set('views', __dirname + '/views');
 
    app.use(express.bodyParser());
    app.use(device.capture());
 
    device.enableViewRouting(app);
});
 
app.get('/', function(req, res) {
    res.render('index.ejs');
})

If the request comes from a phone device then the response will render views/phone/index.ejs view with views/phone/layout.ejs as layout. If it comes from another type of device then it will render the default views/index.ejs with the default views/index.ejs. Simply add a folder below your views root with the device type code (phone, tablet, tv or desktop) for the device type overrides. Several combinations are supported. Please check the tests for more examples.

You also have an ignore option:

app.get('/', function(req, res) {
    res.render('index.ejs', { ignoreViewRouting: true });
})

View routing feature uses the express-partials module for layout detection. If you would like to turn it off, you can use the noPartials option (be advised that by doing this you can no longer use the master\partial layout built into express-device, but you can route to full views):

app.configure(function(){
    app.set('view engine', 'ejs');
    app.set('view options', { layout: true });
    app.set('views', __dirname + '/views');
 
    app.use(express.bodyParser());
    app.use(device.capture());
 
    device.enableViewRouting(app, {
        "noPartials":true
    });
});
 
app.get('/', function(req, res) {
    res.render('index.ejs');
})

contributors

where to go from here?

Currently express-device is on version 0.3.11. There are a couple of things that I have in mind to add, such as:

trying to parse the OS from the request

Feel free to add issues with your own ideas or make pull requests (prefered method).

license

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

express-device

express-device

why express-device?

how it came to be?

how to use it?

contributors

where to go from here?

license

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