解决chrome浏览器无法得到window.showModalDialog返回值

父页面：

 function openwindows(){
			var obj = new Object();
		    //obj.ordernumlst=new Array("001","002","003");
		    var retval = window.showModalDialog("ordervideo.jsp?orderIds="+"0010,0020,0030",obj,"dialogWidth=500px;dialogHeight=500px");
		    
		    //for chrome
		    if(retval == undefined) {
		    	retval = window.returnValue;
		    }
		    alert(retval);
      }

子页面：

function onload(){
    var flag = '<%=request.getAttribute("resultflag")%>';
    if(flag == 'error') {
    	//for chrome
	   	if(window.opener != undefined) {
	   		window.opener.returnValue = flag;
	   	} else {
	  		window.returnValue=flag;
	   	}
	    window.close();
    }
    else if (flag == 'save') {
    	//for chrome
    	if(window.opener != undefined) {
    		window.opener.returnValue = flag;
    	} else {
	  		window.returnValue=flag;
    	}
  	    window.close();
    }
}