# Yahoo! UI Library

### animation 2.8.1

Yahoo! UI Library > animation > Scroll.js (source view)
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    (function() {
    /**
     * Anim subclass for scrolling elements to a position defined by the "scroll"
     * member of "attributes".  All "scroll" members are arrays with x, y scroll positions.
     * <p>Usage: <code>var myAnim = new YAHOO.util.Scroll(el, { scroll: { to: [0, 800] } }, 1, YAHOO.util.Easing.easeOut);</code></p>
     * @class Scroll
     * @namespace YAHOO.util
     * @requires YAHOO.util.Anim
     * @requires YAHOO.util.AnimMgr
     * @requires YAHOO.util.Easing
     * @requires YAHOO.util.Bezier
     * @requires YAHOO.util.Dom
     * @requires YAHOO.util.Event
     * @requires YAHOO.util.CustomEvent
     * @extends YAHOO.util.ColorAnim
     * @constructor
     * @param {String or HTMLElement} el Reference to the element that will be animated
     * @param {Object} attributes The attribute(s) to be animated.
     * Each attribute is an object with at minimum a "to" or "by" member defined.
     * Additional optional members are "from" (defaults to current value), "units" (defaults to "px").
     * All attribute names use camelCase.
     * @param {Number} duration (optional, defaults to 1 second) Length of animation (frames or seconds), defaults to time-based
     * @param {Function} method (optional, defaults to YAHOO.util.Easing.easeNone) Computes the values that are applied to the attributes per frame (generally a YAHOO.util.Easing method)
     */
        var Scroll = function(el, attributes, duration,  method) {
            if (el) { // dont break existing subclasses not using YAHOO.extend
                Scroll.superclass.constructor.call(this, el, attributes, duration, method);
            }
        };

        Scroll.NAME = 'Scroll';

        // shorthand
        var Y = YAHOO.util;
        YAHOO.extend(Scroll, Y.ColorAnim);

        var superclass = Scroll.superclass;
        var proto = Scroll.prototype;

        proto.doMethod = function(attr, start, end) {
            var val = null;

            if (attr == 'scroll') {
                val = [
                    this.method(this.currentFrame, start[0], end[0] - start[0], this.totalFrames),
                    this.method(this.currentFrame, start[1], end[1] - start[1], this.totalFrames)
                ];

            } else {
                val = superclass.doMethod.call(this, attr, start, end);
            }
            return val;
        };

        proto.getAttribute = function(attr) {
            var val = null;
            var el = this.getEl();

            if (attr == 'scroll') {
                val = [ el.scrollLeft, el.scrollTop ];
            } else {
                val = superclass.getAttribute.call(this, attr);
            }

            return val;
        };

        proto.setAttribute = function(attr, val, unit) {
            var el = this.getEl();

            if (attr == 'scroll') {
                el.scrollLeft = val[0];
                el.scrollTop = val[1];
            } else {
                superclass.setAttribute.call(this, attr, val, unit);
            }
        };

        Y.Scroll = Scroll;
    })();

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