For even more robustness:
function getIframeWindow(iframe_object) {
var doc;
if (iframe_object.contentWindow) {
return iframe_object.contentWindow;
}
if (iframe_object.window) {
return iframe_object.window;
}
if (!doc && iframe_object.contentDocument) {
doc = iframe_object.contentDocument;
}
if (!doc && iframe_object.document) {
doc = iframe_object.document;
}
if (doc && doc.defaultView) {
return doc.defaultView;
}
if (doc && doc.parentWindow) {
return doc.parentWindow;
}
return undefined;
}
and
...
var el = document.getElementById('targetFrame');
var frame_win = getIframeWindow(el);
if (frame_win) {
frame_win.reset();
...
}
...