# Yahoo! UI Library

### event 3.0.0

Yahoo! UI Library > event > event-ready-base.js (source view)
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    /*
     * DOM event listener abstraction layer
     * @module event
     * @submodule event-base
     */

    (function() {

    // Unlike most of the library, this code has to be executed as soon as it is
    // introduced into the page -- and it should only be executed one time
    // regardless of the number of instances that use it.

    var GLOBAL_ENV = YUI.Env,

        C = YUI.config,

        D = C.doc,

        POLL_INTERVAL = C.pollInterval || 40,

        _ready = function(e) {
            GLOBAL_ENV._ready();
        };

        if (!GLOBAL_ENV._ready) {

            GLOBAL_ENV._ready = function() {
                if (!GLOBAL_ENV.DOMReady) {
                    GLOBAL_ENV.DOMReady=true;

                    // Remove the DOMContentLoaded (FF/Opera/Safari)
                    if (D.removeEventListener) {
                        D.removeEventListener("DOMContentLoaded", _ready, false);
                    }
                }
            };

            // create custom event

    /*! DOMReady: based on work by: Dean Edwards/John Resig/Matthias Miller/Diego Perini */

            // Internet Explorer: use the readyState of a defered script.
            // This isolates what appears to be a safe moment to manipulate
            // the DOM prior to when the document's readyState suggests
            // it is safe to do so.
            if (navigator.userAgent.match(/MSIE/)) {

                if (self !== self.top) {
                    document.onreadystatechange = function() {
                        if (document.readyState == 'complete') {
                            document.onreadystatechange = null;
                            _ready();
                        }
                    };
                } else {

                    GLOBAL_ENV._dri = setInterval(function() {
                        try {
                            // throws an error if doc is not ready
                            document.documentElement.doScroll('left');
                            clearInterval(GLOBAL_ENV._dri);
                            GLOBAL_ENV._dri = null;
                            _ready();
                        } catch (ex) {
                        }
                    }, POLL_INTERVAL);
                }

            // FireFox, Opera, Safari 3+: These browsers provide a event for this
            // moment.
            } else {
                D.addEventListener("DOMContentLoaded", _ready, false);
            }

            /////////////////////////////////////////////////////////////
        }

    })();

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