# Yahoo! UI Library

### YAHOO Global 2.5.0

Yahoo! UI Library > yahoo > YAHOO.js (source view)

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    /**
     * The YAHOO object is the single global object used by YUI Library.  It
     * contains utility function for setting up namespaces, inheritance, and
     * logging.  YAHOO.util, YAHOO.widget, and YAHOO.example are namespaces
     * created automatically for and used by the library.
     * @module yahoo
     * @title  YAHOO Global
     */

    /**
     * YAHOO_config is not included as part of the library.  Instead it is an
     * object that can be defined by the implementer immediately before
     * including the YUI library.  The properties included in this object
     * will be used to configure global properties needed as soon as the
     * library begins to load.
     * @class YAHOO_config
     * @static
     */

    /**
     * A reference to a function that will be executed every time a YAHOO module
     * is loaded.  As parameter, this function will receive the version
     * information for the module. See <a href="YAHOO.env.html#getVersion">
     * YAHOO.env.getVersion</a> for the description of the version data structure.
     * @property listener
     * @type Function
     * @static
     * @default undefined
     */

    /**
     * Set to true if the library will be dynamically loaded after window.onload.
     * Defaults to false
     * @property injecting
     * @type boolean
     * @static
     * @default undefined
     */

    /**
     * Instructs the yuiloader component to dynamically load yui components and
     * their dependencies.  See the yuiloader documentation for more information
     * about dynamic loading
     * @property load
     * @static
     * @default undefined
     * @see yuiloader
     */

    /**
     * Forces the use of the supplied locale where applicable in the library
     * @property locale
     * @type string
     * @static
     * @default undefined
     */

    if (typeof YAHOO == "undefined" || !YAHOO) {
        /**
         * The YAHOO global namespace object.  If YAHOO is already defined, the
         * existing YAHOO object will not be overwritten so that defined
         * namespaces are preserved.
         * @class YAHOO
         * @static
         */
        var YAHOO = {};
    }

    /**
     * Returns the namespace specified and creates it if it doesn't exist
     * <pre>
     * YAHOO.namespace("property.package");
     * YAHOO.namespace("YAHOO.property.package");
     * </pre>
     * Either of the above would create YAHOO.property, then
     * YAHOO.property.package
     *
     * Be careful when naming packages. Reserved words may work in some browsers
     * and not others. For instance, the following will fail in Safari:
     * <pre>
     * YAHOO.namespace("really.long.nested.namespace");
     * </pre>
     * This fails because "long" is a future reserved word in ECMAScript
     *
     * @method namespace
     * @static
     * @param  {String*} arguments 1-n namespaces to create
     * @return {Object}  A reference to the last namespace object created
     */
    YAHOO.namespace = function() {
        var a=arguments, o=null, i, j, d;
        for (i=0; i<a.length; i=i+1) {
            d=a[i].split(".");
            o=YAHOO;

            // YAHOO is implied, so it is ignored if it is included
            for (j=(d[0] == "YAHOO") ? 1 : 0; j<d.length; j=j+1) {
                o[d[j]]=o[d[j]] || {};
                o=o[d[j]];
            }
        }

        return o;
    };

    /**
     * Uses YAHOO.widget.Logger to output a log message, if the widget is
     * available.
     *
     * @method log
     * @static
     * @param  {String}  msg  The message to log.
     * @param  {String}  cat  The log category for the message.  Default
     *                        categories are "info", "warn", "error", time".
     *                        Custom categories can be used as well. (opt)
     * @param  {String}  src  The source of the the message (opt)
     * @return {Boolean}      True if the log operation was successful.
     */
    YAHOO.log = function(msg, cat, src) {
        var l=YAHOO.widget.Logger;
        if(l && l.log) {
            return l.log(msg, cat, src);
        } else {
            return false;
        }
    };

    /**
     * Registers a module with the YAHOO object
     * @method register
     * @static
     * @param {String}   name    the name of the module (event, slider, etc)
     * @param {Function} mainClass a reference to class in the module.  This
     *                             class will be tagged with the version info
     *                             so that it will be possible to identify the
     *                             version that is in use when multiple versions
     *                             have loaded
     * @param {Object}   data      metadata object for the module.  Currently it
     *                             is expected to contain a "version" property
     *                             and a "build" property at minimum.
     */
    YAHOO.register = function(name, mainClass, data) {
        var mods = YAHOO.env.modules;
        if (!mods[name]) {
            mods[name] = { versions:[], builds:[] };
        }
        var m=mods[name],v=data.version,b=data.build,ls=YAHOO.env.listeners;
        m.name = name;
        m.version = v;
        m.build = b;
        m.versions.push(v);
        m.builds.push(b);
        m.mainClass = mainClass;
        // fire the module load listeners
        for (var i=0;i<ls.length;i=i+1) {
            ls[i](m);
        }
        // label the main class
        if (mainClass) {
            mainClass.VERSION = v;
            mainClass.BUILD = b;
        } else {
            YAHOO.log("mainClass is undefined for module " + name, "warn");
        }
    };

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