转：
var iframe = document.createElement("iframe");
iframe.src = "http://www.planabc.net";
if (iframe.attachEvent){
iframe.attachEvent("onload", function(){
alert("Local iframe is now loaded.");
});
} else {
iframe.onload = function(){
alert("Local iframe is now loaded.");
};
}
document.body.appendChild(iframe);
或者：
var iframe = document.getElementById("frm_txt_ParentId");
iframe.src = "dialog/common-mselect.aspx?dialogName=select_customer&selectionMode=1&filter=";
if (iframe.attachEvent) {
//IE
iframe.attachEvent("onload", function () {
alert("111111Local iframe is now loaded.");
});
} else {
//非IE
iframe.onload = function () {
alert("222Local iframe is now loaded.");
};
}