1741058 - iframe content disappears right after it is displayed

Status: RESOLVED WORKSFORME

(Core :: DOM: Navigation, defect, P2)

Description

[Alice0775 White]

Steps to reproduce:

1. https://code-kitchen.dev/html/button/
2. optional , reload (F5)

Actual results:
The iframe content disappears right after it is displayed.

Expected results:
The iframe content should not disappear.
Chrome works as expected.

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=26510fca112eff4a2f8a714f4c2a6079103fc6a7&tochange=e763b6e09a4914247ab86b3600acac8562e6c1d1

Comment 1

[Alice0775 White]

Attachment: Nightly96.0a1 .vs. Chrome95

Comment 2

[Anny Gakhokidze [:annyG]]

Initial observation - I can't reproduce this on mac for Firefox 96.0a1 (2021-11-15) with or without fission. I should check if this can be reproduced on linux.

Comment 3

[Chris Peterson [:cpeterson]]

needinfo'ing kmag because he said he would investigate.

Comment 4

[Alice0775 White]

I can also reproduce the issue in Nightly96.0a1(20211115215316) Ubuntu20.04.

Comment 5

[Thomas Wisniewski [:twisniewski]]

This doesn't reproduce for me on the current nightly on OSX unless I have the devtools open, and even then only intermittently. That implies there's a timing/race issue here, which superficially sounds a lot like bug 1736570.. And digging in deeper, it does seem to be triggered the same way as bug 1736570:

1. The iframe is in the source markup to begin with: <iframe class="browser__content iframe-tag" data-v-5cf017ac></iframe>
2. As one of the page's JS component mounts, they set the still-empty iframe's innerHTML:

      mounted: function () {
        var html = this.$el.querySelector('#slot-html code').innerText,
        style = '';
        this.$slots.css && (style = this.getStyleTag());
        var iframe = this.$el.querySelector('.iframe-tag'),
        t = iframe.contentDocument || iframe.contentWindow.document;
        t.getElementsByTagName('body') [0].innerHTML = this.unescapeHtml('<div id="main-content">'.concat(html, '</div>').concat(style).concat('<style>img { max-width: 100%; } body { font-family: UI Gothic, Meiryo, sans-serif; }</style>')),
        this.height ? iframe.style.height = ''.concat(this.height, 'px') : setTimeout((function () {
          var e = t.getElementById('main-content').clientHeight;
          iframe.style.height = ''.concat(e + 50, 'px')
        }), 1000)
      },

3. Somehow the document for that iframe becomes blank after this point (it has no body innerHTML).

Even when I add a breakpoint on the line immediately after the one which sets the frame's innerHTML, the problem still intermittently reproduces, so it seems like the page itself isn't triggering this behavior.

Indeed, if I log the value of the iframe's document's readyState (t.readyState in that function above), it's uninitialized when the iframe is broken, and complete when it is not. Also, when I similarly log the value of t, both it and its body element are no longer attached by the time I inspect them, when the iframe is broken (otherwise the devtools take me to the expected point in the inspector when it's working).

So it seems that this is the same issue we're seeing in bug 1736570.

Comment 6

[Alice0775 White]

I can still reproduce the problem in Nightly98.0a1(20220202093701) Ubuntu20.04.
And I confirmed that the try build of Bug 1736570 Comment#76 solved this problem too.

Comment 7

[Hsin-Yi Tsai (she/her) [:hsinyi]]

Now that bug 1736570 was landed, I cannot reproduce this problem.
Would you please help verify? Thank you!

Comment 8

[Hsin-Yi Tsai (she/her) [:hsinyi]]

(In reply to Hsin-Yi Tsai [:hsinyi] from comment #7)

Now that bug 1736570 was landed, I cannot reproduce this problem.
Would you please help verify? Thank you!

Oh, NO ... it's getting harder to reproduce. But if I reload the page more times, I still encounter this issue.

Comment 9

[Alice0775 White]

And I found a more reliable STR for the latest Nightly 99.0a1.

STR:

1. Open https://code-kitchen.dev/html/button/ in first tab
2. Open new tab
3. Close the first tab
4. Reopen closed tab

Actual results:
The iframe content disappears right after it is displayed.

Comment 10

[Olli Pettay [:smaug][[e-mail]]]

Hmm, "Reopen closed tab" smells like session (re)store.

Comment 11

[Alice0775 White]

FYI, On the good build(i.e, before Bug 1589102), it works as expected with STR of comment#9.

Comment 12

[Hsin-Yi Tsai (she/her) [:hsinyi]]

It seems to be much easier for me to reproduce, if I open https://code-kitchen.dev/html/button/ in the first tab. (How would the position of the tab matters? Is it just a coincidence?) Then press F5 to reload. Repeat pressing F5 several times (about 5 times). The issue is reproduced.

Comment 13

[Hsin-Yi Tsai (she/her) [:hsinyi]]

Changing the severity to S3 as the situation has been mitigated after bug 1736570. Please let me know if you see this differently.

Comment 14

[Hsin-Yi Tsai (she/her) [:hsinyi]]

Clear some old NI requested by me.

Comment 15

[Alice0775 White]

WFM on 115esr as well as 121.0a1.