API: dom Dom.js (YUI Library)

# Yahoo! UI Library

### dom 2.8.1

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    /**
     * The dom module provides helper methods for manipulating Dom elements.
     * @module dom
     *
     */

    (function() {
        // for use with generateId (global to save state if Dom is overwritten)
        YAHOO.env._id_counter = YAHOO.env._id_counter || 0;

        // internal shorthand
        var Y = YAHOO.util,
            lang = YAHOO.lang,
            UA = YAHOO.env.ua,
            trim = YAHOO.lang.trim,
            propertyCache = {}, // for faster hyphen converts
            reCache = {}, // cache className regexes
            RE_TABLE = /^t(?:able|d|h)$/i, // for _calcBorders
            RE_COLOR = /color$/i,

            // DOM aliases
            document = window.document,
            documentElement = document.documentElement,

            // string constants
            OWNER_DOCUMENT = 'ownerDocument',
            DEFAULT_VIEW = 'defaultView',
            DOCUMENT_ELEMENT = 'documentElement',
            COMPAT_MODE = 'compatMode',
            OFFSET_LEFT = 'offsetLeft',
            OFFSET_TOP = 'offsetTop',
            OFFSET_PARENT = 'offsetParent',
            PARENT_NODE = 'parentNode',
            NODE_TYPE = 'nodeType',
            TAG_NAME = 'tagName',
            SCROLL_LEFT = 'scrollLeft',
            SCROLL_TOP = 'scrollTop',
            GET_BOUNDING_CLIENT_RECT = 'getBoundingClientRect',
            GET_COMPUTED_STYLE = 'getComputedStyle',
            CURRENT_STYLE = 'currentStyle',
            CSS1_COMPAT = 'CSS1Compat',
            _BACK_COMPAT = 'BackCompat',
            _CLASS = 'class', // underscore due to reserved word
            CLASS_NAME = 'className',
            EMPTY = '',
            SPACE = ' ',
            C_START = '(?:^|\\s)',
            C_END = '(?= |$)',
            G = 'g',
            POSITION = 'position',
            FIXED = 'fixed',
            RELATIVE = 'relative',
            LEFT = 'left',
            TOP = 'top',
            MEDIUM = 'medium',
            BORDER_LEFT_WIDTH = 'borderLeftWidth',
            BORDER_TOP_WIDTH = 'borderTopWidth',

        // brower detection
            isOpera = UA.opera,
            isSafari = UA.webkit,
            isGecko = UA.gecko,
            isIE = UA.ie;

        /**
         * Provides helper methods for DOM elements.
         * @namespace YAHOO.util
         * @class Dom
         * @requires yahoo, event
         */
        Y.Dom = {
            CUSTOM_ATTRIBUTES: (!documentElement.hasAttribute) ? { // IE < 8
                'for': 'htmlFor',
                'class': CLASS_NAME
            } : { // w3c
                'htmlFor': 'for',
                'className': _CLASS
            },

            DOT_ATTRIBUTES: {},

            /**
             * Returns an HTMLElement reference.
             * @method get
             * @param {String | HTMLElement |Array} el Accepts a string to use as an ID for getting a DOM reference, an actual DOM reference, or an Array of IDs and/or HTMLElements.
             * @return {HTMLElement | Array} A DOM reference to an HTML element or an array of HTMLElements.
             */
            get: function(el) {
                var id, nodes, c, i, len, attr;

                if (el) {
                    if (el[NODE_TYPE] || el.item) { // Node, or NodeList
                        return el;
                    }

                    if (typeof el === 'string') { // id
                        id = el;
                        el = document.getElementById(el);
                        attr = (el) ? el.attributes : null;
                        if (el && attr && attr.id && attr.id.value === id) { // IE: avoid false match on "name" attribute
                            return el;
                        } else if (el && document.all) { // filter by name
                            el = null;
                            nodes = document.all[id];
                            for (i = 0, len = nodes.length; i < len; ++i) {
                                if (nodes[i].id === id) {
                                    return nodes[i];
                                }
                            }
                        }
                        return el;
                    }

                    if (YAHOO.util.Element && el instanceof YAHOO.util.Element) {
                        el = el.get('element');
                    }

                    if ('length' in el) { // array-like
                        c = [];
                        for (i = 0, len = el.length; i < len; ++i) {
                            c[c.length] = Y.Dom.get(el[i]);
                        }

                        return c;
                    }

                    return el; // some other object, just pass it back
                }

                return null;
            },

            getComputedStyle: function(el, property) {
                if (window[GET_COMPUTED_STYLE]) {
                    return el[OWNER_DOCUMENT][DEFAULT_VIEW][GET_COMPUTED_STYLE](el, null)[property];
                } else if (el[CURRENT_STYLE]) {
                    return Y.Dom.IE_ComputedStyle.get(el, property);
                }
            },

            /**
             * Normalizes currentStyle and ComputedStyle.
             * @method getStyle
             * @param {String | HTMLElement |Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
             * @param {String} property The style property whose value is returned.
             * @return {String | Array} The current value of the style property for the element(s).
             */
            getStyle: function(el, property) {
                return Y.Dom.batch(el, Y.Dom._getStyle, property);
            },

            // branching at load instead of runtime
            _getStyle: function() {
                if (window[GET_COMPUTED_STYLE]) { // W3C DOM method
                    return function(el, property) {
                        property = (property === 'float') ? property = 'cssFloat' :
                                Y.Dom._toCamel(property);

                        var value = el.style[property],
                            computed;

                        if (!value) {
                            computed = el[OWNER_DOCUMENT][DEFAULT_VIEW][GET_COMPUTED_STYLE](el, null);
                            if (computed) { // test computed before touching for safari
                                value = computed[property];
                            }
                        }

                        return value;
                    };
                } else if (documentElement[CURRENT_STYLE]) {
                    return function(el, property) {
                        var value;

                        switch(property) {
                            case 'opacity' :// IE opacity uses filter
                                value = 100;
                                try { // will error if no DXImageTransform
                                    value = el.filters['DXImageTransform.Microsoft.Alpha'].opacity;

                                } catch(e) {
                                    try { // make sure its in the document
                                        value = el.filters('alpha').opacity;
                                    } catch(err) {
                                        YAHOO.log('getStyle: IE filter failed',
                                                'error', 'Dom');
                                    }
                                }
                                return value / 100;
                            case 'float': // fix reserved word
                                property = 'styleFloat'; // fall through
                            default:
                                property = Y.Dom._toCamel(property);
                                value = el[CURRENT_STYLE] ? el[CURRENT_STYLE][property] : null;
                                return ( el.style[property] || value );
                        }
                    };
                }
            }(),

            /**
             * Wrapper for setting style properties of HTMLElements.  Normalizes "opacity" across modern browsers.
             * @method setStyle
             * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
             * @param {String} property The style property to be set.
             * @param {String} val The value to apply to the given property.
             */
            setStyle: function(el, property, val) {
                Y.Dom.batch(el, Y.Dom._setStyle, { prop: property, val: val });
            },

            _setStyle: function() {
                if (isIE) {
                    return function(el, args) {
                        var property = Y.Dom._toCamel(args.prop),
                            val = args.val;

                        if (el) {
                            switch (property) {
                                case 'opacity':
                                    if ( lang.isString(el.style.filter) ) { // in case not appended
                                        el.style.filter = 'alpha(opacity=' + val * 100 + ')';

                                        if (!el[CURRENT_STYLE] || !el[CURRENT_STYLE].hasLayout) {
                                            el.style.zoom = 1; // when no layout or cant tell
                                        }
                                    }
                                    break;
                                case 'float':
                                    property = 'styleFloat';
                                default:
                                el.style[property] = val;
                            }
                        } else {
                            YAHOO.log('element ' + el + ' is undefined', 'error', 'Dom');
                        }
                    };
                } else {
                    return function(el, args) {
                        var property = Y.Dom._toCamel(args.prop),
                            val = args.val;
                        if (el) {
                            if (property == 'float') {
                                property = 'cssFloat';
                            }
                            el.style[property] = val;
                        } else {
                            YAHOO.log('element ' + el + ' is undefined', 'error', 'Dom');
                        }
                    };
                }

            }(),

            /**
             * Gets the current position of an element based on page coordinates.
             * Element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
             * @method getXY
             * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM
             * reference, or an Array of IDs and/or HTMLElements
             * @return {Array} The XY position of the element(s)
             */
            getXY: function(el) {
                return Y.Dom.batch(el, Y.Dom._getXY);
            },

            _canPosition: function(el) {
                return ( Y.Dom._getStyle(el, 'display') !== 'none' && Y.Dom._inDoc(el) );
            },

            _getXY: function() {
                if (document[DOCUMENT_ELEMENT][GET_BOUNDING_CLIENT_RECT]) {
                    return function(node) {
                        var scrollLeft, scrollTop, box, doc,
                            off1, off2, mode, bLeft, bTop,
                            floor = Math.floor, // TODO: round?
                            xy = false;

                        if (Y.Dom._canPosition(node)) {
                            box = node[GET_BOUNDING_CLIENT_RECT]();
                            doc = node[OWNER_DOCUMENT];
                            scrollLeft = Y.Dom.getDocumentScrollLeft(doc);
                            scrollTop = Y.Dom.getDocumentScrollTop(doc);
                            xy = [floor(box[LEFT]), floor(box[TOP])];

                            if (isIE && UA.ie < 8) { // IE < 8: viewport off by 2
                                off1 = 2;
                                off2 = 2;
                                mode = doc[COMPAT_MODE];

                                if (UA.ie === 6) {
                                    if (mode !== _BACK_COMPAT) {
                                        off1 = 0;
                                        off2 = 0;
                                    }
                                }

                                if ((mode === _BACK_COMPAT)) {
                                    bLeft = _getComputedStyle(doc[DOCUMENT_ELEMENT], BORDER_LEFT_WIDTH);
                                    bTop = _getComputedStyle(doc[DOCUMENT_ELEMENT], BORDER_TOP_WIDTH);
                                    if (bLeft !== MEDIUM) {
                                        off1 = parseInt(bLeft, 10);
                                    }
                                    if (bTop !== MEDIUM) {
                                        off2 = parseInt(bTop, 10);
                                    }
                                }

                                xy[0] -= off1;
                                xy[1] -= off2;

                            }

                            if ((scrollTop || scrollLeft)) {
                                xy[0] += scrollLeft;
                                xy[1] += scrollTop;
                            }

                            // gecko may return sub-pixel (non-int) values
                            xy[0] = floor(xy[0]);
                            xy[1] = floor(xy[1]);
                        } else {
                            YAHOO.log('getXY failed: element not positionable (either not in a document or not displayed)', 'error', 'Dom');
                        }

                        return xy;
                    };
                } else {
                    return function(node) { // ff2, safari: manually calculate by crawling up offsetParents
                        var docScrollLeft, docScrollTop,
                            scrollTop, scrollLeft,
                            bCheck,
                            xy = false,
                            parentNode = node;

                        if  (Y.Dom._canPosition(node) ) {
                            xy = [node[OFFSET_LEFT], node[OFFSET_TOP]];
                            docScrollLeft = Y.Dom.getDocumentScrollLeft(node[OWNER_DOCUMENT]);
                            docScrollTop = Y.Dom.getDocumentScrollTop(node[OWNER_DOCUMENT]);

                            // TODO: refactor with !! or just falsey
                            bCheck = ((isGecko || UA.webkit > 519) ? true : false);

                            // TODO: worth refactoring for TOP/LEFT only?
                            while ((parentNode = parentNode[OFFSET_PARENT])) {
                                xy[0] += parentNode[OFFSET_LEFT];
                                xy[1] += parentNode[OFFSET_TOP];
                                if (bCheck) {
                                    xy = Y.Dom._calcBorders(parentNode, xy);
                                }
                            }

                            // account for any scrolled ancestors
                            if (Y.Dom._getStyle(node, POSITION) !== FIXED) {
                                parentNode = node;

                                while ((parentNode = parentNode[PARENT_NODE]) && parentNode[TAG_NAME]) {
                                    scrollTop = parentNode[SCROLL_TOP];
                                    scrollLeft = parentNode[SCROLL_LEFT];

                                    //Firefox does something funky with borders when overflow is not visible.
                                    if (isGecko && (Y.Dom._getStyle(parentNode, 'overflow') !== 'visible')) {
                                            xy = Y.Dom._calcBorders(parentNode, xy);
                                    }

                                    if (scrollTop || scrollLeft) {
                                        xy[0] -= scrollLeft;
                                        xy[1] -= scrollTop;
                                    }
                                }
                                xy[0] += docScrollLeft;
                                xy[1] += docScrollTop;

                            } else {
                                //Fix FIXED position -- add scrollbars
                                if (isOpera) {
                                    xy[0] -= docScrollLeft;
                                    xy[1] -= docScrollTop;
                                } else if (isSafari || isGecko) {
                                    xy[0] += docScrollLeft;
                                    xy[1] += docScrollTop;
                                }
                            }
                            //Round the numbers so we get sane data back
                            xy[0] = Math.floor(xy[0]);
                            xy[1] = Math.floor(xy[1]);
                        } else {
                            YAHOO.log('getXY failed: element not positionable (either not in a document or not displayed)', 'error', 'Dom');
                        }
                        return xy;
                    };
                }
            }(), // NOTE: Executing for loadtime branching

            /**
             * Gets the current X position of an element based on page coordinates.  The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
             * @method getX
             * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements
             * @return {Number | Array} The X position of the element(s)
             */
            getX: function(el) {
                var f = function(el) {
                    return Y.Dom.getXY(el)[0];
                };

                return Y.Dom.batch(el, f, Y.Dom, true);
            },

            /**
             * Gets the current Y position of an element based on page coordinates.  Element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
             * @method getY
             * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements
             * @return {Number | Array} The Y position of the element(s)
             */
            getY: function(el) {
                var f = function(el) {
                    return Y.Dom.getXY(el)[1];
                };

                return Y.Dom.batch(el, f, Y.Dom, true);
            },

            /**
             * Set the position of an html element in page coordinates, regardless of how the element is positioned.
             * The element(s) must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
             * @method setXY
             * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements
             * @param {Array} pos Contains X & Y values for new position (coordinates are page-based)
             * @param {Boolean} noRetry By default we try and set the position a second time if the first fails
             */
            setXY: function(el, pos, noRetry) {
                Y.Dom.batch(el, Y.Dom._setXY, { pos: pos, noRetry: noRetry });
            },

            _setXY: function(node, args) {
                var pos = Y.Dom._getStyle(node, POSITION),
                    setStyle = Y.Dom.setStyle,
                    xy = args.pos,
                    noRetry = args.noRetry,

                    delta = [ // assuming pixels; if not we will have to retry
                        parseInt( Y.Dom.getComputedStyle(node, LEFT), 10 ),
                        parseInt( Y.Dom.getComputedStyle(node, TOP), 10 )
                    ],

                    currentXY,
                    newXY;

                if (pos == 'static') { // default to relative
                    pos = RELATIVE;
                    setStyle(node, POSITION, pos);
                }

                currentXY = Y.Dom._getXY(node);

                if (!xy || currentXY === false) { // has to be part of doc to have xy
                    YAHOO.log('xy failed: node not available', 'error', 'Node');
                    return false;
                }

                if ( isNaN(delta[0]) ) {// in case of 'auto'
                    delta[0] = (pos == RELATIVE) ? 0 : node[OFFSET_LEFT];
                }
                if ( isNaN(delta[1]) ) { // in case of 'auto'
                    delta[1] = (pos == RELATIVE) ? 0 : node[OFFSET_TOP];
                }

                if (xy[0] !== null) { // from setX
                    setStyle(node, LEFT, xy[0] - currentXY[0] + delta[0] + 'px');
                }

                if (xy[1] !== null) { // from setY
                    setStyle(node, TOP, xy[1] - currentXY[1] + delta[1] + 'px');
                }

                if (!noRetry) {
                    newXY = Y.Dom._getXY(node);

                    // if retry is true, try one more time if we miss
                   if ( (xy[0] !== null && newXY[0] != xy[0]) ||
                        (xy[1] !== null && newXY[1] != xy[1]) ) {
                       Y.Dom._setXY(node, { pos: xy, noRetry: true });
                   }
                }

                YAHOO.log('setXY setting position to ' + xy, 'info', 'Node');
            },

            /**
             * Set the X position of an html element in page coordinates, regardless of how the element is positioned.
             * The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
             * @method setX
             * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
             * @param {Int} x The value to use as the X coordinate for the element(s).
             */
            setX: function(el, x) {
                Y.Dom.setXY(el, [x, null]);
            },

            /**
             * Set the Y position of an html element in page coordinates, regardless of how the element is positioned.
             * The element must be part of the DOM tree to have page coordinates (display:none or elements not appended return false).
             * @method setY
             * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
             * @param {Int} x To use as the Y coordinate for the element(s).
             */
            setY: function(el, y) {
                Y.Dom.setXY(el, [null, y]);
            },

            /**
             * Returns the region position of the given element.
             * The element must be part of the DOM tree to have a region (display:none or elements not appended return false).
             * @method getRegion
             * @param {String | HTMLElement | Array} el Accepts a string to use as an ID, an actual DOM reference, or an Array of IDs and/or HTMLElements.
             * @return {Region | Array} A Region or array of Region instances containing "top, left, bottom, right" member data.
             */
            getRegion: function(el) {
                var f = function(el) {
                    var region = false;
                    if ( Y.Dom._canPosition(el) ) {
                        region = Y.Region.getRegion(el);
                        YAHOO.log('getRegion returning ' + region, 'info', 'Dom');
                    } else {
                        YAHOO.log('getRegion failed: element not positionable (either not in a document or not displayed)', 'error', 'Dom');
                    }

                    return region;
                };

                return Y.Dom.batch(el, f, Y.Dom, true);
            },

            /**
             * Returns the width of the client (viewport).
             * @method getClientWidth
             * @deprecated Now using getViewportWidth.  This interface left intact for back compat.
             * @return {Int} The width of the viewable area of the page.
             */
            getClientWidth: function() {
                return Y.Dom.getViewportWidth();
            },

            /**
             * Returns the height of the client (viewport).
             * @method getClientHeight
             * @deprecated Now using getViewportHeight.  This interface left intact for back compat.
             * @return {Int} The height of the viewable area of the page.
             */
            getClientHeight: function() {
                return Y.Dom.getViewportHeight();
            },

            /**
             * Returns an array of HTMLElements with the given class.
             * For optimized performance, include a tag and/or root node when possible.
             * Note: This method operates against a live collection, so modifying the
             * collection in the callback (removing/appending nodes, etc.) will have
             * side effects.  Instead you should iterate the returned nodes array,
             * as you would with the native "getElementsByTagName" method.
             * @method getElementsByClassName
             * @param {String} className The class name to match against
             * @param {String} tag (optional) The tag name of the elements being collected
             * @param {String | HTMLElement} root (optional) The HTMLElement or an ID to use as the starting point.
             * This element is not included in the className scan.
             * @param {Function} apply (optional) A function to apply to each element when found
             * @param {Any} o (optional) An optional arg that is passed to the supplied method
             * @param {Boolean} overrides (optional) Whether or not to override the scope of "method" with "o"
             * @return {Array} An array of elements that have the given class name
             */
            getElementsByClassName: function(className, tag, root, apply, o, overrides) {
                tag = tag || '*';
                root = (root) ? Y.Dom.get(root) : null || document;
                if (!root) {
                    return [];
                }

                var nodes = [],
                    elements = root.getElementsByTagName(tag),
                    hasClass = Y.Dom.hasClass;

                for (var i = 0, len = elements.length; i < len; ++i) {
                    if ( hasClass(elements[i], className) ) {
                        nodes[nodes.length] = elements[i];
                    }
                }

                if (apply) {
                    Y.Dom.batch(nodes, apply, o, overrides);
                }

                return nodes;
            },

            /**
             * Determines whether an HTMLElement has the given className.
             * @method hasClass
             * @param {String | HTMLElement | Array} el The element or collection to test
             * @param {String} className the class name to search for
             * @return {Boolean | Array} A boolean value or array of boolean values
             */
            hasClass: function(el, className) {
                return Y.Dom.batch(el, Y.Dom._hasClass, className);
            },

            _hasClass: function(el, className) {
                var ret = false,
                    current;

                if (el && className) {
                    current = Y.Dom._getAttribute(el, CLASS_NAME) || EMPTY;
                    if (className.exec) {
                        ret = className.test(current);
                    } else {
                        ret = className && (SPACE + current + SPACE).
                            indexOf(SPACE + className + SPACE) > -1;
                    }
                } else {
                    YAHOO.log('hasClass called with invalid arguments', 'warn', 'Dom');
                }

                return ret;
            },

            /**
             * Adds a class name to a given element or collection of elements.
             * @method addClass
             * @param {String | HTMLElement | Array} el The element or collection to add the class to
             * @param {String} className the class name to add to the class attribute
             * @return {Boolean | Array} A pass/fail boolean or array of booleans
             */
            addClass: function(el, className) {
                return Y.Dom.batch(el, Y.Dom._addClass, className);
            },

            _addClass: function(el, className) {
                var ret = false,
                    current;

                if (el && className) {
                    current = Y.Dom._getAttribute(el, CLASS_NAME) || EMPTY;
                    if ( !Y.Dom._hasClass(el, className) ) {
                        Y.Dom.setAttribute(el, CLASS_NAME, trim(current + SPACE + className));
                        ret = true;
                    }
                } else {
                    YAHOO.log('addClass called with invalid arguments', 'warn', 'Dom');
                }

                return ret;
            },

            /**
             * Removes a class name from a given element or collection of elements.
             * @method removeClass
             * @param {String | HTMLElement | Array} el The element or collection to remove the class from
             * @param {String} className the class name to remove from the class attribute
             * @return {Boolean | Array} A pass/fail boolean or array of booleans
             */
            removeClass: function(el, className) {
                return Y.Dom.batch(el, Y.Dom._removeClass, className);
            },

            _removeClass: function(el, className) {
                var ret = false,
                    current,
                    newClass,
                    attr;

                if (el && className) {
                    current = Y.Dom._getAttribute(el, CLASS_NAME) || EMPTY;
                    Y.Dom.setAttribute(el, CLASS_NAME, current.replace(Y.Dom._getClassRegex(className), EMPTY));

                    newClass = Y.Dom._getAttribute(el, CLASS_NAME);
                    if (current !== newClass) { // else nothing changed
                        Y.Dom.setAttribute(el, CLASS_NAME, trim(newClass)); // trim after comparing to current class
                        ret = true;

                        if (Y.Dom._getAttribute(el, CLASS_NAME) === '') { // remove class attribute if empty
                            attr = (el.hasAttribute && el.hasAttribute(_CLASS)) ? _CLASS : CLASS_NAME;
                            YAHOO.log('removeClass removing empty class attribute', 'info', 'Dom');
                            el.removeAttribute(attr);
                        }
                    }

                } else {
                    YAHOO.log('removeClass called with invalid arguments', 'warn', 'Dom');
                }

                return ret;
            },

            /**
             * 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
             */
            replaceClass: function(el, oldClassName, newClassName) {
                return Y.Dom.batch(el, Y.Dom._replaceClass, { from: oldClassName, to: newClassName });
            },

            _replaceClass: function(el, classObj) {
                var className,
                    from,
                    to,
                    ret = false,
                    current;

                if (el && classObj) {
                    from = classObj.from;
                    to = classObj.to;

                    if (!to) {
                        ret = false;
                    }  else if (!from) { // just add if no "from"
                        ret = Y.Dom._addClass(el, classObj.to);
                    } else if (from !== to) { // else nothing to replace
                        // May need to lead with DBLSPACE?
                        current = Y.Dom._getAttribute(el, CLASS_NAME) || EMPTY;
                        className = (SPACE + current.replace(Y.Dom._getClassRegex(from), SPACE + to)).
                                   split(Y.Dom._getClassRegex(to));

                        // insert to into what would have been the first occurrence slot
                        className.splice(1, 0, SPACE + to);
                        Y.Dom.setAttribute(el, CLASS_NAME, trim(className.join(EMPTY)));
                        ret = true;
                    }
                } else {
                    YAHOO.log('replaceClass called with invalid arguments', 'warn', 'Dom');
                }

                return ret;
            },

            /**
             * Returns an ID and applies it to the element "el", if provided.
             * @method generateId
             * @param {String | HTMLElement | Array} el (optional) An optional element array of elements to add an ID to (no ID is added if one is already present).
             * @param {String} prefix (optional) an optional prefix to use (defaults to "yui-gen").
             * @return {String | Array} The generated ID, or array of generated IDs (or original ID if already present on an element)
             */
            generateId: function(el, prefix) {
                prefix = prefix || 'yui-gen';

                var f = function(el) {
                    if (el && el.id) { // do not override existing ID
                        YAHOO.log('generateId returning existing id ' + el.id, 'info', 'Dom');
                        return el.id;
                    }

                    var id = prefix + YAHOO.env._id_counter++;
                    YAHOO.log('generateId generating ' + id, 'info', 'Dom');

                    if (el) {
                        if (el[OWNER_DOCUMENT] && el[OWNER_DOCUMENT].getElementById(id)) { // in case one already exists
                            // use failed id plus prefix to help ensure uniqueness
                            return Y.Dom.generateId(el, id + prefix);
                        }
                        el.id = id;
                    }

                    return id;
                };

                // batch fails when no element, so just generate and return single ID
                return Y.Dom.batch(el, f, Y.Dom, true) || f.apply(Y.Dom, arguments);
            },

            /**
             * Determines whether an HTMLElement is an ancestor of another HTML element in the DOM hierarchy.
             * @method isAncestor
             * @param {String | HTMLElement} haystack The possible ancestor
             * @param {String | HTMLElement} needle The possible descendent
             * @return {Boolean} Whether or not the haystack is an ancestor of needle
             */
            isAncestor: function(haystack, needle) {
                haystack = Y.Dom.get(haystack);
                needle = Y.Dom.get(needle);

                var ret = false;

                if ( (haystack && needle) && (haystack[NODE_TYPE] && needle[NODE_TYPE]) ) {
                    if (haystack.contains && haystack !== needle) { // contains returns true when equal
                        ret = haystack.contains(needle);
                    }
                    else if (haystack.compareDocumentPosition) { // gecko
                        ret = !!(haystack.compareDocumentPosition(needle) & 16);
                    }
                } else {
                    YAHOO.log('isAncestor failed; invalid input: ' + haystack + ',' + needle, 'error', 'Dom');
                }
                YAHOO.log('isAncestor(' + haystack + ',' + needle + ' returning ' + ret, 'info', 'Dom');
                return ret;
            },

            /**
             * Determines whether an HTMLElement is present in the current document.
             * @method inDocument
             * @param {String | HTMLElement} el The element to search for
             * @param {Object} doc An optional document to search, defaults to element's owner document
             * @return {Boolean} Whether or not the element is present in the current document
             */
            inDocument: function(el, doc) {
                return Y.Dom._inDoc(Y.Dom.get(el), doc);
            },

            _inDoc: function(el, doc) {
                var ret = false;
                if (el && el[TAG_NAME]) {
                    doc = doc || el[OWNER_DOCUMENT];
                    ret = Y.Dom.isAncestor(doc[DOCUMENT_ELEMENT], el);
                } else {
                    YAHOO.log('inDocument failed: invalid input', 'error', 'Dom');
                }
                return ret;
            },

            /**
             * Returns an array of HTMLElements that pass the test applied by supplied boolean method.
             * For optimized performance, include a tag and/or root node when possible.
             * Note: This method operates against a live collection, so modifying the
             * collection in the callback (removing/appending nodes, etc.) will have
             * side effects.  Instead you should iterate the returned nodes array,
             * as you would with the native "getElementsByTagName" method.
             * @method getElementsBy
             * @param {Function} method - A boolean method for testing elements which receives the element as its only argument.
             * @param {String} tag (optional) The tag name of the elements being collected
             * @param {String | HTMLElement} root (optional) The HTMLElement or an ID to use as the starting point
             * @param {Function} apply (optional) A function to apply to each element when found
             * @param {Any} o (optional) An optional arg that is passed to the supplied method
             * @param {Boolean} overrides (optional) Whether or not to override the scope of "method" with "o"
             * @return {Array} Array of HTMLElements
             */
            getElementsBy: function(method, tag, root, apply, o, overrides, firstOnly) {
                tag = tag || '*';
                root = (root) ? Y.Dom.get(root) : null || document;

                if (!root) {
                    return [];
                }

                var nodes = [],
                    elements = root.getElementsByTagName(tag);

                for (var i = 0, len = elements.length; i < len; ++i) {
                    if ( method(elements[i]) ) {
                        if (firstOnly) {
                            nodes = elements[i];
                            break;
                        } else {
                            nodes[nodes.length] = elements[i];
                        }
                    }
                }

                if (apply) {
                    Y.Dom.batch(nodes, apply, o, overrides);
                }

                YAHOO.log('getElementsBy returning ' + nodes, 'info', 'Dom');

                return nodes;
            },

            /**
             * Returns the first HTMLElement that passes the test applied by the supplied boolean method.
             * @method getElementBy
             * @param {Function} method - A boolean method for testing elements which receives the element as its only argument.
             * @param {String} tag (optional) The tag name of the elements being collected
             * @param {String | HTMLElement} root (optional) The HTMLElement or an ID to use as the starting point
             * @return {HTMLElement}
             */
            getElementBy: function(method, tag, root) {
                return Y.Dom.getElementsBy(method, tag, root, null, null, null, true);
            },

            /**
             * Runs the supplied method against each item in the Collection/Array.
             * The method is called with the element(s) as the first arg, and the optional param as the second ( method(el, o) ).
             * @method batch
             * @param {String | HTMLElement | Array} el (optional) An element or array of elements to apply the method to
             * @param {Function} method The method to apply to the element(s)
             * @param {Any} o (optional) An optional arg that is passed to the supplied method
             * @param {Boolean} overrides (optional) Whether or not to override the scope of "method" with "o"
             * @return {Any | Array} The return value(s) from the supplied method
             */
            batch: function(el, method, o, overrides) {
                var collection = [],
                    scope = (overrides) ? o : window;

                el = (el && (el[TAG_NAME] || el.item)) ? el : Y.Dom.get(el); // skip get() when possible
                if (el && method) {
                    if (el[TAG_NAME] || el.length === undefined) { // element or not array-like
                        return method.call(scope, el, o);
                    }

                    for (var i = 0; i < el.length; ++i) {
                        collection[collection.length] = method.call(scope, el[i], o);
                    }
                } else {
                    YAHOO.log('batch called with invalid arguments', 'warn', 'Dom');
                    return false;
                }
                return collection;
            },

            /**
             * Returns the height of the document.
             * @method getDocumentHeight
             * @return {Int} The height of the actual document (which includes the body and its margin).
             */
            getDocumentHeight: function() {
                var scrollHeight = (document[COMPAT_MODE] != CSS1_COMPAT || isSafari) ? document.body.scrollHeight : documentElement.scrollHeight,
                    h = Math.max(scrollHeight, Y.Dom.getViewportHeight());

                YAHOO.log('getDocumentHeight returning ' + h, 'info', 'Dom');
                return h;
            },

            /**
             * Returns the width of the document.
             * @method getDocumentWidth
             * @return {Int} The width of the actual document (which includes the body and its margin).
             */
            getDocumentWidth: function() {
                var scrollWidth = (document[COMPAT_MODE] != CSS1_COMPAT || isSafari) ? document.body.scrollWidth : documentElement.scrollWidth,
                    w = Math.max(scrollWidth, Y.Dom.getViewportWidth());
                YAHOO.log('getDocumentWidth returning ' + w, 'info', 'Dom');
                return w;
            },

            /**
             * Returns the current height of the viewport.
             * @method getViewportHeight
             * @return {Int} The height of the viewable area of the page (excludes scrollbars).
             */
            getViewportHeight: function() {
                var height = self.innerHeight, // Safari, Opera
                    mode = document[COMPAT_MODE];

                if ( (mode || isIE) && !isOpera ) { // IE, Gecko
                    height = (mode == CSS1_COMPAT) ?
                            documentElement.clientHeight : // Standards
                            document.body.clientHeight; // Quirks
                }

                YAHOO.log('getViewportHeight returning ' + height, 'info', 'Dom');
                return height;
            },

            /**
             * Returns the current width of the viewport.
             * @method getViewportWidth
             * @return {Int} The width of the viewable area of the page (excludes scrollbars).
             */

            getViewportWidth: function() {
                var width = self.innerWidth,  // Safari
                    mode = document[COMPAT_MODE];

                if (mode || isIE) { // IE, Gecko, Opera
                    width = (mode == CSS1_COMPAT) ?
                            documentElement.clientWidth : // Standards
                            document.body.clientWidth; // Quirks
                }
                YAHOO.log('getViewportWidth returning ' + width, 'info', 'Dom');
                return width;
            },

           /**
             * Returns the nearest ancestor that passes the test applied by supplied boolean method.
             * For performance reasons, IDs are not accepted and argument validation omitted.
             * @method getAncestorBy
             * @param {HTMLElement} node The HTMLElement to use as the starting point
             * @param {Function} method - A boolean method for testing elements which receives the element as its only argument.
             * @return {Object} HTMLElement or null if not found
             */
            getAncestorBy: function(node, method) {
                while ( (node = node[PARENT_NODE]) ) { // NOTE: assignment
                    if ( Y.Dom._testElement(node, method) ) {
                        YAHOO.log('getAncestorBy returning ' + node, 'info', 'Dom');
                        return node;
                    }
                }

                YAHOO.log('getAncestorBy returning null (no ancestor passed test)', 'error', 'Dom');
                return null;
            },

            /**
             * Returns the nearest ancestor with the given className.
             * @method getAncestorByClassName
             * @param {String | HTMLElement} node The HTMLElement or an ID to use as the starting point
             * @param {String} className
             * @return {Object} HTMLElement
             */
            getAncestorByClassName: function(node, className) {
                node = Y.Dom.get(node);
                if (!node) {
                    YAHOO.log('getAncestorByClassName failed: invalid node argument', 'error', 'Dom');
                    return null;
                }
                var method = function(el) { return Y.Dom.hasClass(el, className); };
                return Y.Dom.getAncestorBy(node, method);
            },

            /**
             * Returns the nearest ancestor with the given tagName.
             * @method getAncestorByTagName
             * @param {String | HTMLElement} node The HTMLElement or an ID to use as the starting point
             * @param {String} tagName
             * @return {Object} HTMLElement
             */
            getAncestorByTagName: function(node, tagName) {
                node = Y.Dom.get(node);
                if (!node) {
                    YAHOO.log('getAncestorByTagName failed: invalid node argument', 'error', 'Dom');
                    return null;
                }
                var method = function(el) {
                     return el[TAG_NAME] && el[TAG_NAME].toUpperCase() == tagName.toUpperCase();
                };

                return Y.Dom.getAncestorBy(node, method);
            },

            /**
             * Returns the previous sibling that is an HTMLElement.
             * For performance reasons, IDs are not accepted and argument validation omitted.
             * Returns the nearest HTMLElement sibling if no method provided.
             * @method getPreviousSiblingBy
             * @param {HTMLElement} node The HTMLElement to use as the starting point
             * @param {Function} method A boolean function used to test siblings
             * that receives the sibling node being tested as its only argument
             * @return {Object} HTMLElement or null if not found
             */
            getPreviousSiblingBy: function(node, method) {
                while (node) {
                    node = node.previousSibling;
                    if ( Y.Dom._testElement(node, method) ) {
                        return node;
                    }
                }
                return null;
            },

            /**
             * Returns the previous sibling that is an HTMLElement
             * @method getPreviousSibling
             * @param {String | HTMLElement} node The HTMLElement or an ID to use as the starting point
             * @return {Object} HTMLElement or null if not found
             */
            getPreviousSibling: function(node) {
                node = Y.Dom.get(node);
                if (!node) {
                    YAHOO.log('getPreviousSibling failed: invalid node argument', 'error', 'Dom');
                    return null;
                }

                return Y.Dom.getPreviousSiblingBy(node);
            },

            /**
             * Returns the next HTMLElement sibling that passes the boolean method.
             * For performance reasons, IDs are not accepted and argument validation omitted.
             * Returns the nearest HTMLElement sibling if no method provided.
             * @method getNextSiblingBy
             * @param {HTMLElement} node The HTMLElement to use as the starting point
             * @param {Function} method A boolean function used to test siblings
             * that receives the sibling node being tested as its only argument
             * @return {Object} HTMLElement or null if not found
             */
            getNextSiblingBy: function(node, method) {
                while (node) {
                    node = node.nextSibling;
                    if ( Y.Dom._testElement(node, method) ) {
                        return node;
                    }
                }
                return null;
            },

            /**
             * Returns the next sibling that is an HTMLElement
             * @method getNextSibling
             * @param {String | HTMLElement} node The HTMLElement or an ID to use as the starting point
             * @return {Object} HTMLElement or null if not found
             */
            getNextSibling: function(node) {
                node = Y.Dom.get(node);
                if (!node) {
                    YAHOO.log('getNextSibling failed: invalid node argument', 'error', 'Dom');
                    return null;
                }

                return Y.Dom.getNextSiblingBy(node);
            },

            /**
             * Returns the first HTMLElement child that passes the test method.
             * @method getFirstChildBy
             * @param {HTMLElement} node The HTMLElement to use as the starting point
             * @param {Function} method A boolean function used to test children
             * that receives the node being tested as its only argument
             * @return {Object} HTMLElement or null if not found
             */
            getFirstChildBy: function(node, method) {
                var child = ( Y.Dom._testElement(node.firstChild, method) ) ? node.firstChild : null;
                return child || Y.Dom.getNextSiblingBy(node.firstChild, method);
            },

            /**
             * Returns the first HTMLElement child.
             * @method getFirstChild
             * @param {String | HTMLElement} node The HTMLElement or an ID to use as the starting point
             * @return {Object} HTMLElement or null if not found
             */
            getFirstChild: function(node, method) {
                node = Y.Dom.get(node);
                if (!node) {
                    YAHOO.log('getFirstChild failed: invalid node argument', 'error', 'Dom');
                    return null;
                }
                return Y.Dom.getFirstChildBy(node);
            },

            /**
             * Returns the last HTMLElement child that passes the test method.
             * @method getLastChildBy
             * @param {HTMLElement} node The HTMLElement to use as the starting point
             * @param {Function} method A boolean function used to test children
             * that receives the node being tested as its only argument
             * @return {Object} HTMLElement or null if not found
             */
            getLastChildBy: function(node, method) {
                if (!node) {
                    YAHOO.log('getLastChild failed: invalid node argument', 'error', 'Dom');
                    return null;
                }
                var child = ( Y.Dom._testElement(node.lastChild, method) ) ? node.lastChild : null;
                return child || Y.Dom.getPreviousSiblingBy(node.lastChild, method);
            },

            /**
             * Returns the last HTMLElement child.
             * @method getLastChild
             * @param {String | HTMLElement} node The HTMLElement or an ID to use as the starting point
             * @return {Object} HTMLElement or null if not found
             */
            getLastChild: function(node) {
                node = Y.Dom.get(node);
                return Y.Dom.getLastChildBy(node);
            },

            /**
             * Returns an array of HTMLElement childNodes that pass the test method.
             * @method getChildrenBy
             * @param {HTMLElement} node The HTMLElement to start from
             * @param {Function} method A boolean function used to test children
             * that receives the node being tested as its only argument
             * @return {Array} A static array of HTMLElements
             */
            getChildrenBy: function(node, method) {
                var child = Y.Dom.getFirstChildBy(node, method),
                    children = child ? [child] : [];

                Y.Dom.getNextSiblingBy(child, function(node) {
                    if ( !method || method(node) ) {
                        children[children.length] = node;
                    }
                    return false; // fail test to collect all children
                });

                return children;
            },

            /**
             * Returns an array of HTMLElement childNodes.
             * @method getChildren
             * @param {String | HTMLElement} node The HTMLElement or an ID to use as the starting point
             * @return {Array} A static array of HTMLElements
             */
            getChildren: function(node) {
                node = Y.Dom.get(node);
                if (!node) {
                    YAHOO.log('getChildren failed: invalid node argument', 'error', 'Dom');
                }

                return Y.Dom.getChildrenBy(node);
            },

            /**
             * Returns the left scroll value of the document
             * @method getDocumentScrollLeft
             * @param {HTMLDocument} document (optional) The document to get the scroll value of
             * @return {Int}  The amount that the document is scrolled to the left
             */
            getDocumentScrollLeft: function(doc) {
                doc = doc || document;
                return Math.max(doc[DOCUMENT_ELEMENT].scrollLeft, doc.body.scrollLeft);
            },

            /**
             * Returns the top scroll value of the document
             * @method getDocumentScrollTop
             * @param {HTMLDocument} document (optional) The document to get the scroll value of
             * @return {Int}  The amount that the document is scrolled to the top
             */
            getDocumentScrollTop: function(doc) {
                doc = doc || document;
                return Math.max(doc[DOCUMENT_ELEMENT].scrollTop, doc.body.scrollTop);
            },

            /**
             * Inserts the new node as the previous sibling of the reference node
             * @method insertBefore
             * @param {String | HTMLElement} newNode The node to be inserted
             * @param {String | HTMLElement} referenceNode The node to insert the new node before
             * @return {HTMLElement} The node that was inserted (or null if insert fails)
             */
            insertBefore: function(newNode, referenceNode) {
                newNode = Y.Dom.get(newNode);
                referenceNode = Y.Dom.get(referenceNode);

                if (!newNode || !referenceNode || !referenceNode[PARENT_NODE]) {
                    YAHOO.log('insertAfter failed: missing or invalid arg(s)', 'error', 'Dom');
                    return null;
                }

                return referenceNode[PARENT_NODE].insertBefore(newNode, referenceNode);
            },

            /**
             * Inserts the new node as the next sibling of the reference node
             * @method insertAfter
             * @param {String | HTMLElement} newNode The node to be inserted
             * @param {String | HTMLElement} referenceNode The node to insert the new node after
             * @return {HTMLElement} The node that was inserted (or null if insert fails)
             */
            insertAfter: function(newNode, referenceNode) {
                newNode = Y.Dom.get(newNode);
                referenceNode = Y.Dom.get(referenceNode);

                if (!newNode || !referenceNode || !referenceNode[PARENT_NODE]) {
                    YAHOO.log('insertAfter failed: missing or invalid arg(s)', 'error', 'Dom');
                    return null;
                }

                if (referenceNode.nextSibling) {
                    return referenceNode[PARENT_NODE].insertBefore(newNode, referenceNode.nextSibling);
                } else {
                    return referenceNode[PARENT_NODE].appendChild(newNode);
                }
            },

            /**
             * Creates a Region based on the viewport relative to the document.
             * @method getClientRegion
             * @return {Region} A Region object representing the viewport which accounts for document scroll
             */
            getClientRegion: function() {
                var t = Y.Dom.getDocumentScrollTop(),
                    l = Y.Dom.getDocumentScrollLeft(),
                    r = Y.Dom.getViewportWidth() + l,
                    b = Y.Dom.getViewportHeight() + t;

                return new Y.Region(t, r, b, l);
            },

            /**
             * Provides a normalized attribute interface.
             * @method setAttribute
             * @param {String | HTMLElement} el The target element for the attribute.
             * @param {String} attr The attribute to set.
             * @param {String} val The value of the attribute.
             */
            setAttribute: function(el, attr, val) {
                Y.Dom.batch(el, Y.Dom._setAttribute, { attr: attr, val: val });
            },

            _setAttribute: function(el, args) {
                var attr = Y.Dom._toCamel(args.attr),
                    val = args.val;

                if (el && el.setAttribute) {
                    if (Y.Dom.DOT_ATTRIBUTES[attr]) {
                        el[attr] = val;
                    } else {
                        attr = Y.Dom.CUSTOM_ATTRIBUTES[attr] || attr;
                        el.setAttribute(attr, val);
                    }
                } else {
                    YAHOO.log('setAttribute method not available for ' + el, 'error', 'Dom');
                }
            },

            /**
             * Provides a normalized attribute interface.
             * @method getAttribute
             * @param {String | HTMLElement} el The target element for the attribute.
             * @param {String} attr The attribute to get.
             * @return {String} The current value of the attribute.
             */
            getAttribute: function(el, attr) {
                return Y.Dom.batch(el, Y.Dom._getAttribute, attr);
            },

            _getAttribute: function(el, attr) {
                var val;
                attr = Y.Dom.CUSTOM_ATTRIBUTES[attr] || attr;

                if (el && el.getAttribute) {
                    val = el.getAttribute(attr, 2);
                } else {
                    YAHOO.log('getAttribute method not available for ' + el, 'error', 'Dom');
                }

                return val;
            },

            _toCamel: function(property) {
                var c = propertyCache;

                function tU(x,l) {
                    return l.toUpperCase();
                }

                return c[property] || (c[property] = property.indexOf('-') === -1 ?
                                        property :
                                        property.replace( /-([a-z])/gi, tU ));
            },

            _getClassRegex: function(className) {
                var re;
                if (className !== undefined) { // allow empty string to pass
                    if (className.exec) { // already a RegExp
                        re = className;
                    } else {
                        re = reCache[className];
                        if (!re) {
                            // escape special chars (".", "[", etc.)
                            className = className.replace(Y.Dom._patterns.CLASS_RE_TOKENS, '\\$1');
                            re = reCache[className] = new RegExp(C_START + className + C_END, G);
                        }
                    }
                }
                return re;
            },

            _patterns: {
                ROOT_TAG: /^body|html$/i, // body for quirks mode, html for standards,
                CLASS_RE_TOKENS: /([\.\(\)\^\$\*\+\?\|\[\]\{\}\\])/g
            },

            _testElement: function(node, method) {
                return node && node[NODE_TYPE] == 1 && ( !method || method(node) );
            },

            _calcBorders: function(node, xy2) {
                var t = parseInt(Y.Dom[GET_COMPUTED_STYLE](node, BORDER_TOP_WIDTH), 10) || 0,
                    l = parseInt(Y.Dom[GET_COMPUTED_STYLE](node, BORDER_LEFT_WIDTH), 10) || 0;
                if (isGecko) {
                    if (RE_TABLE.test(node[TAG_NAME])) {
                        t = 0;
                        l = 0;
                    }
                }
                xy2[0] += l;
                xy2[1] += t;
                return xy2;
            }
        };

        var _getComputedStyle = Y.Dom[GET_COMPUTED_STYLE];
        // fix opera computedStyle default color unit (convert to rgb)
        if (UA.opera) {
            Y.Dom[GET_COMPUTED_STYLE] = function(node, att) {
                var val = _getComputedStyle(node, att);
                if (RE_COLOR.test(att)) {
                    val = Y.Dom.Color.toRGB(val);
                }

                return val;
            };

        }

        // safari converts transparent to rgba(), others use "transparent"
        if (UA.webkit) {
            Y.Dom[GET_COMPUTED_STYLE] = function(node, att) {
                var val = _getComputedStyle(node, att);

                if (val === 'rgba(0, 0, 0, 0)') {
                    val = 'transparent';
                }

                return val;
            };

        }

        if (UA.ie && UA.ie >= 8 && document.documentElement.hasAttribute) { // IE 8 standards
            Y.Dom.DOT_ATTRIBUTES.type = true; // IE 8 errors on input.setAttribute('type')
        }
    })();

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