html class tweaking

head.js

/**
 * `html` class tweaking
 */
(function() {

  var html = document.getElementsByTagName("html")[0];

  /* helpers */

  var hasClass = function(node, cls) {
    return new RegExp("(\\s|^)" + cls + "(\\s|$)").test(node.className);
  };

  var addClass = function(node, cls) {
    if (hasClass(node, cls)) {
      return;
    }
    return node.className = "" + node.className + " " + cls;
  };

  var removeClass = function(node, cls) {
    if (!hasClass(node, cls)) {
      return;
    }
    node.className = node.className
      .replace(new RegExp("(\\s|^)" + cls + "(\\s|$)"), " ")
      .replace(/\s+/g, " ").replace(/^\s|\s$/, "");
  };

  /* UA detection */
  
  var ua = (function(){
    var ua = {};
    var navigator = window.navigator;
    var platforms = [
      { property: 'platform', regex: /iPhone/i, identity: 'iPhone' },
      { property: 'platform', regex: /iPod/i, identity: 'iPod' },
      { property: 'userAgent', regex: /iPad/i, identity: 'iPad' },
      { property: 'userAgent', regex: /Blackberry/i, identity: 'Blackberry' },
      { property: 'userAgent', regex: /Android/i, identity: 'Android' },
      { property: 'platform', regex: /Mac/i, identity: 'Mac' },
      { property: 'platform', regex: /Win/i, identity: 'Windows' },
      { property: 'platform', regex: /Linux/i, identity: 'Linux' }
    ];
    for(var i=0, l=platforms.length, platform; i<l; i++){
      platform = platforms[i];
      ua[platform.identity] = platform.regex.test(navigator[platform.property]);
    }
    return ua;
  })();
  
  /* do it */
  
  if(ua.Windows) {
    addClass(html, 'os-win');
  }
  if(ua.Mac) {
    addClass(html, 'os-mac');
  }

}());