public/javascripts/yui/dom/dom-debug.js
function(el, oldClassName, newClassName) {
            return Y.Dom.batch(el, Y.Dom._replaceClass, { from: oldClassName, to: newClassName });
        }
function(el, oldClassName, newClassName) {
            return Y.Dom.batch(el, Y.Dom._replaceClass, { from: oldClassName, to: newClassName });
        }
function ( el , oldClassName , newClassName ) { return Y . Dom . batch ( el , Y . Dom . _replaceClass , { from : oldClassName , to : newClassName } ) ; }
Replace a class with another class for a given element or collection of elements.
If no oldClassName is present, the newClassName is simply added.
@method replaceClass
@param {String | HTMLElement | Array} el The element or collection to remove the class from
@param {String} oldClassName the class name to be replaced
@param {String} newClassName the class name that will be replacing the old class name
@return {Boolean | Array} A pass/fail boolean or array of booleans
Replace a class with another class for a given element or collection of elements . If no oldClassName is present the newClassName is simply added .