不影响原有的onload方法的前提下，在页面中增加onload的执行方法

        function addOnloadEvent(fnc)
        {
            if (typeof window.addEventListener != "undefined" )
                window.addEventListener( "load", fnc, false );
            else if ( typeof window.attachEvent != "undefined" )
            {
                window.attachEvent( "onload", fnc );
            } 
            else 
            {
                if ( window.onload != null ) 
                {
                    var oldOnload = window.onload;window.onload = function ( e ) {
                                                                                     oldOnload( e );
                                                                                     window[fnc]();
                                                                                 };
                } 
                else 
                    window.onload = fnc;
            }
       
        }