in book/master_middleman/source/javascripts/waypoints/noframeworkAdapter.js [147:156]
NoFrameworkAdapter.prototype.toggleClass = function(className, addClass) {
var check = classNameRegExp(className);
if (check.test(this.element.className)) {
if (!addClass) {
this.removeClass(className);
}
} else {
this.element.className += ' ' + className;
}
}