A mobile web dev script to toggle through portrait & landscape classes on a document's body element.

orientation.js

/*global document */
var orientation;
(function () {
    "use strict";
    orientation = function () {
        var isPortrait, isLandscape;
        isPortrait = document.body.className.indexOf('portrait') !== -1;
        isLandscape = document.body.className.indexOf('landscape') !== -1;
        document.body.className = document.body.className.split(' portrait ').join('');
        document.body.className = document.body.className.split(' landscape ').join('');
        if (!isPortrait && !isLandscape) {
            document.body.className += ' portrait ';
        } else if (!isLandscape) {
            document.body.className += ' landscape ';
        }
    };
    orientation();
}());