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# Node

The Node Utility provides an expressive way to collect, create, and manipulate DOM nodes. Each `Node` instance represents an underlying DOM node, and each `NodeList` represents a collection of DOM nodes.

In addition to wrapping the basic DOM API and handling cross browser issues, `Node`s provide convenient methods for managing CSS classes, setting or animating styles, subscribing to events, updating or dynamically loading content, and lots more.

Note: The `Y.get()`, `node.query()`, and `node.queryAll()` methods have been removed. Use `Y.one()`, `node.one()`, and `node.all()`.

## Getting Started

To include the source files for Node and its dependencies, first load the YUI seed file if you haven't already loaded it.

    <script src="http://yui.yahooapis.com/3.10.3/build/yui/yui-min.js"></script>

Next, create a new YUI instance for your application and populate it with the modules you need by specifying them as arguments to the `YUI().use()` method. YUI will automatically load any dependencies required by the modules you specify.

    <script>
    // Create a new YUI instance and populate it with the required modules.
    YUI().use('node', function (Y) {
        // Node is available and ready for use. Add implementation
        // code here.
    });
    </script>

For more information on creating YUI instances and on the `use()` method, see the documentation for the YUI Global Object.

## Using Nodes

`Node` is the interface for DOM operations in YUI 3. The Node API is based on the standard DOM API, and provides additional sugar properties and methods that make common operations easier, and implementation code more concise. Developers familiar with the standard DOM API will find Node instances to be very familiar.

### Getting a Node

    // Use Y.one( [css selector string] )
    var node = Y.one('#main');

    // Or pass an HTML element
    var bodyNode = Y.one(document.body);

The simplest way to get a `Node` instance is using your YUI instance's `one` method. `Y.one` accepts either an existing DOM element or a CSS selector. If a selector string is used, the first matching element is used. NodeLists are also available for working with collections of `Node`s.

Note: CSS3 selector support is not included by default with Node. Add support by including the "selector-css3" module in your `use()` statement.

### Creating Nodes and Modifying Content

    // Create a new Node
    var item = Y.Node.create('<li id="step3" class="highlight"><em>Profit</em></li>');

    // Replace the content in a Node
    Y.one("#hello").setHTML("<h1>Hello, <em>World</em>!</h1>");

    // Append new markup inside a Node
    bodyNode.append("<p>This is the end, beautiful friend, the end.</p>");

`Node`s have methods for appending, prepending, replacing, and inserting content. The static method `Y.Node.create()` is provided to create new `Node`s that you want to work with a bit more before attaching them to the DOM.

As noted in DOM Methods below, the standard DOM API methods, such as `appendChild` and `insertBefore` are also available to manipulate the DOM structure.

### Accessing Node Properties

    var imgNode = Y.one('#preview');
    var labelNode = imgNode.get('nextSibling'); // Node instance

    var bigSrc = thumbnail.get('src').slice(0, -4) + '-big.jpg';

    imgNode.set('src', bigSrc);
    imgNode.set('title', thumbnail.get('title');
    labelNode.setHTML(thumbnail.get('title'));

Properties of the underlying DOM node are accessed via the `Node` instance's `set` and `get` methods. For simple property types (strings, numbers, booleans), these pass directly to/from the underlying node, but properties that normally return DOM nodes return `Node` instances instead.

### DOM Events

    Y.one('#demo').on('click', function(e) {
        e.preventDefault();
        alert('event: ' + e.type + ' target: ' + e.target.get('tagName'));
    });

Use the `on` method to add an event listener to a `Node` instance. The event object passed as the first argument to each listener is an event facade that, like the Node API, normalizes browser differences and provides a standard API for working with DOM events based on the W3C standard. All properties of the event object that would normally return DOM elements return `Node` instances.

For more details, check out the Event user guide.

### DOM Methods

    var tasklist = Y.one('ul#tasklist');
    var item3 = tasklist.appendChild( Y.one('#pending .item-3') );

    item3.addClass('highlight');

The `Node` API provides all of the DOM methods you would expect, plus a few extras to help with common tasks. As with properties and events, any methods that would normally return DOM nodes instead return `Node` instances.

### Working With Collections of Nodes

`NodeList` is the class for working with groups of `Node`s.

    var doneTasks = Y.all('#tasklist .completed');

    // NodeLists host most Node methods for simple iterative operations
    doneTasks.removeClass('highlight');

    // or call each() to do more work on each Node
    doneTasks.each(function (taskNode) {
        taskNode.transition({ opacity: 0 }, function () {
            completedTasklist.appendChild(this);
        });
    });

The `Y.all` method is the simplest way to get a `NodeList`, but throughout the library, any property or method that would return a collection of HTML elements will return a `NodeList`.

    var nodelist = taskList.get('childNodes');

The `NodeList` provides a `Node`-like interface for manipulating multiple `Node`s through a single interface. The `NodeList` API is a pared-down version of the `Node` API for simple operations, plus common `Array` methods such as `slice()` and `pop()` for modifying the internal list of wrapped `Node`s, and some general purpose iteration methods such as `each()` and `some()`.

### Query a Node's Descendants

    var node = Y.one('#demo');

    var firstPara = node.one('p');

    if (firstPara) { // might be null
        // adds "bar" to the first paragraph descendant of #demo
        firstPara.addClass('bar');
    }

    // adds class "syntax-highlight" to all <pre> descendants of #demo
    node.all('pre').addClass('syntax-highlight');

Like `Y.one()` and `Y.all()`, `Node` instances have `one()` and `all()` methods for querying their descendants.

Using selectors to capture descendants is faster and more convenient than relying on DOM properties such as `childNodes` and `nextSibling` since you don't have to worry about working around text nodes or recursing into element subtrees.

Using `one()` and `all()` from a `Node` rather than `Y` can aid performance in large pages as well, because `Y.one()` and `Y.all()` always query from the `document`, which will scan a lot more elements.

For more information on selector queries, see the following W3C specifications:

- CSS Level 3 Selectors
- Selectors API

Note: CSS3 selector support is not included by default with Node, you will need to include the "selector-css3" module for CSS3 support.

## ARIA Support

The Node interface has support for ARIA. When used with Node's built-in support for CSS selector queries, it is easy to both apply and manage a Node's roles, states and properties.

The ARIA Roles, States and Properties enhance the semantics of HTML, allowing developers to more accurately describe the intended purpose of a region of a page, or a DHTML widget, thereby improving the user experience for users of assistive technology, such as screen readers.

Apply any of the ARIA Roles, States and Properties via the `set` method. For example, to apply the role of `toolbar` to a `<div>` with an id of "toolbar":

    var node = Y.one('#toolbar').set('role', 'toolbar');

Node's built-in support for CSS selector queries, method chaining, and ability to set multiple attributes on a single Node instance makes it especially easy to apply the ARIA Roles, States, and Properties when building DHTML widgets with a large subtree. For example, when building a menubar widget it is necessary to apply a role of `menubar` to the root DOM element representing the menubar, and the role of `menu` to the root DOM element representing each submenu. Additionally, as each submenu is hidden by default, the `aria-hidden` state will need to be applied to each submenu as well. The Node interface makes it possible to do all of this in one line of code:

    Y.one('#root').set('role', 'menubar').all('.menu').setAttrs({ role: 'menu', 'aria-hidden': true });

## Migration Table

The following table is included to help users migrating from YUI 2. Most of the functionality from `YAHOO.util.Dom` is available via `Node`.

Note In the snippets below, `myNode` is an instance of `Node`. Methods that normally would return DOM nodes now return Node instances.

2.x `YAHOO.util.???` | 3.0
--- | ---
    Dom.get('elementId');
    Y.one('#elementId');
    Dom.getElementsBy(someFilterFunction);
    myNode.all('selectorString');
    Dom.getElementsByClassName('highlight');
    myNode.all('.highlight');
    Dom.getChildren(el);
    myNode.get('children');
    Dom.getChildrenBy(someFilterFunction);
    myNode.all('selectorString');
    Dom.getFirstChild(parentEl);
    myNode.one('*');
    Dom.getFirstChildBy(someFilterFunction);
    myNode.one('> selectorString');
    Dom.getLastChild(el);
    Dom.getLastChildBy(someFilterFunction);
    myNode.get('children').slice(-1).item(0);
    // OR target the node with a selector
    myNode.one('> selector:last-of-type');
    Dom.getNextSibling(el);
    Dom.getNextSiblingBy(someFilterFunction);
    Dom.getPreviousSibling(el);
    Dom.getPreviousSiblingBy(someFilterFunction);
    myNode.next();
    myNode.next('selectorString');
    myNode.previous();
    myNode.previous('selectorString');
    Dom.getAncestorBy(someFilterFunction);
    Dom.getAncestorByClassName('highlight');
    Dom.getAncestorByTagName('pre');
    myNode.ancestor(someFilterFunction);
    myNode.ancestor('.highlight');
    myNode.ancestor('pre');
    Dom.isAncestor(ancestorEl, el);
    ancestorNode.contains(myNode);
    Dom.insertAfter(el, afterEl);
    Dom.insertBefore(el, beforeNode);
    afterNode.insert(myNode, 'after');
    beforeNode.insert(myNode, 'before');
    Dom.addClass('highlight');
    myNode.addClass('highlight');
    Dom.removeClass(el, 'highlight');
    myNode.removeClass('highlight');
    Dom.replaceClass(el, 'high', 'low');
    myNode.replaceClass('high', 'low');
    Dom.hasClass(el, 'highlight');
    myNode.hasClass('highlight');
    Dom.getStyle(el, 'backgroundColor');
    myNode.getStyle('backgroundColor');
    Dom.setStyle(el, 'borderColor', '#C0FFEE');
    myNode.setStyle('borderColor', '#C0FFEE');
    Dom.getXY(el);
    Dom.getX(el);
    Dom.getY(el);
    myNode.getXY();
    myNode.getX();
    myNode.getY();
    Dom.setXY(el, [ 500, 300 ]);
    Dom.setX(el, 500);
    Dom.setY(el, 300);
    myNode.setXY([ 500, 300 ]);
    myNode.setX(500);
    myNode.setY(300);
    Dom.inDocument(el);
    myNode.inDoc();
    Dom.batch(elementArray,
        Dom.addClass, 'highlight');
    myNodelist.addClass('highlight');
    // OR
    myNodelist.each(function (node) {
        node.addClass('highlight')
    });
    // OR
    Y.Array.each(myNodelist, function (node) {
        node.addClass('highlight');
    });
    Dom.generateId();
    Y.guid();
    Dom.getViewportHeight();
    Dom.getViewportWidth();
    myNode.get('winHeight');
    myNode.get('winWidth');
    Dom.getDocumentHeight();
    Dom.getDocumentWidth();
    myNode.get('docHeight');
    myNode.get('docWidth');
    Dom.getClientRegion();
    myNode.get('viewportRegion');
    Dom.getRegion(el);
    myNode.get('region');
    Dom.getDocumentScrollLeft();
    Dom.getDocumentScrollTop();
    myNode.get('docScrollX');
    myNode.get('docScrollY');