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

function openwindows(){
var obj = new Object();
var retval = window.showModalDialog("ordervideo.jsp?rderIds="+"0010,0020,0030",obj,"dialogWidth=500px;dialogHeight=500px");

//for chrome
if(retval == undefined) {
retval = window.returnValue;
}
alert(retval);
}

function onload(){

//for chrome
if(window.opener != undefined) {
window.opener.returnValue = flag;
} else {
window.returnValue=flag;
}
window.close();

}