[whatwg] Should events be paused on detached iframes?
Ben Lerner
blerner at cs.washington.edu
Tue Aug 24 13:30:03 PDT 2010
There seems to be a bit of disagreement among browsers about how event
loops and iframes interact when an iframe is removed and then reinserted
into its parent document. Consider the following two documents: the
parent document has a button that removes or reattaches an iframe to the
document, while the second simply sets an interval to update the page
content.
Page1.html:
<!DOCTYPE HTML>
<html>
<body>
<p><button onclick="toggleInDoc();">Show/hide</button></p>
<iframe id="test" src="page2.html"></iframe>
<script>
var test = document.getElementById("test");
function toggleInDoc() {
if (test.parentNode == null)
document.body.appendChild(test);
else
document.body.removeChild(test);
}
</script>
</body>
</html>
Page2.html:
<!DOCTYPE HTML>
<html>
<body>
<p id="test"></p>
<script>
window.setInterval(function() {
document.getElementById("test").innerHTML += "."; }, 500);
</script>
</body>
</html>
Assume the user waits until the interval has fired several times, then
presses the button, waits a while, and presses it again. There are
three possible outcomes:
1. When the iframe is reattached, the inner page reloads. This seems to
go beyond the wording of the spec, which says only "When an iframe
element is first inserted into a document, the user agent must create a
nested browsing context, and then process the iframe attributes for the
first time." (This isn't the first time the iframe is inserted into the
document, so we shouldn't process the iframe attributes again.)
2. The interval (and presumably, all events) in the iframe is paused
while it's been detached (since the document is no longer fully active,
but it also has not been discarded because of the global reference to
its container element).
3. The interval (and presumably, all events) continues to fire while
it's been detached, and the content of page2 will have changed while
it's been detached from page1.
So far, Chrome 6, Opera 10.6 and Firefox 3.6 follow #1, and IE 8 follows
#3. My reading of the "fully active" clause of the spec leads me to
expect #2. Which of these behaviors is the desired one? And/or, would
it be desirable to permit authors to specify which behavior they intend?
Thanks,
~ben
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