File Under: CSS, JavaScript

Adapt.js Offers JavaScript Alternative to CSS Media Queries

With the mobile web comes a new set of design problems: how do you fit your content on a much smaller screen, and, more generally, how do you make your site look good no matter what size screen it’s on? The growing consensus is that Responsive Web Design — websites that adapt to the size of the user’s screen — is the way forward.

For many developers that means using @media queries to selectively target the device screen size and orientation through CSS.

While the @media approach is a good one, it won’t work for every site. That’s why Nathan Smith, creator of the 960 Grid System, has released Adapt.js, a lightweight JavaScript library (894 bytes minified) that allows you to specify a list of stylesheets and the screen sizes for which they should be loaded. Essentially Adapt.js does the work of @media, but will work in any browser, even those that don’t understand @media.

All you need to do is include Adapt.js in your pages and then define the sizes and stylesheets to go with them. Here’s the code from Smith’s example:

var ADAPT_CONFIG = {
  // Where is your CSS?
  path: 'assets/css/',

  // First range entry is the minimum.
  // Last range entry is the maximum.
  // Should have at least one "to" range.
  range: [
    '760px            = mobile.css',
    '760px  to 980px  = 720.css',
    '980px  to 1280px = 960.css',
    '1280px to 1600px = 1200.css',
    '1600px to 1920px = 1560.css',
    '1920px           = fluid.css'
  ]
};

While using JavaScript to load CSS might seem a bit strange, even if you use @media queries you’re still going to need some kind of polyfill (usually JavaScript-based) to handle those browsers that don’t know what to do with @media rules.

Of course Adapt.js isn’t right for every situation. Smith has a very nice take on the debate over @media, JavaScript, separate mobile websites and other options for dealing with the small screen:

As with any field in which technological methods are open for debate, there is the danger of religious fanaticism, where we each rally behind a respective technique and defend it vehemently. I would advise you to consider your audience, weigh the options, and find an approach that makes sense for that particular context.

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