var domReady = function( fn ) {

    var isReady = false,

        ready = function(){

            if(!isReady){

                typeof fn === 'function' && fn.call(document);

                isReady = true;

            }

        },

        DOMContentLoaded = function() {

            if ( document.addEventListener ) {

                document.removeEventListener( "DOMContentLoaded", DOMContentLoaded, false );

                ready();

            } else if ( document.readyState === "complete" ) {

                document.detachEvent( "onreadystatechange", DOMContentLoaded );

                ready();

            }

        };

    if ( document.readyState === "complete" ) {

        setTimeout( ready, 1 );

    } else if ( document.addEventListener ) {

        document.addEventListener( "DOMContentLoaded", DOMContentLoaded, false );

        window.addEventListener( "load", ready, false );

    } else {

        document.attachEvent( "onreadystatechange", DOMContentLoaded );

        window.attachEvent( "onload", ready );

        var top = false;

        try {

            top = window.frameElement == null && document.documentElement;

        } catch(e) {}

        if ( top && top.doScroll ) {

            (function doScrollCheck() {

                if ( !isReady ) {

                    try {

                        top.doScroll("left");

                    } catch(e) {

                        return setTimeout( doScrollCheck, 50 );

                    }

                    ready();

                }

            })();

        }

    }

};

//调用

domReady(function(){

    alert(this.getElementById('div1').innerHTML);

});