1627844 - invalid value for HTMLIFrameElement instance's contentWindow.document.readyState "uninitialized"

Status: NEW

(Core :: DOM: Core & HTML, defect, P3)

Description

[divinity76]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Safari/537.36

Steps to reproduce:

unfortunately i don't have a live url to reproduce it, also i am running version the outdated version "Firefox 74.0" from Ubuntu 18.04 repo (i know Ubuntu/Canonical does something to the code, but don't think it's related to the bug) but basically (but not exactly) i ran the html:

<iframe id="buggy" src="page_that_loads_content_type_text_html_charset_utf8"></iframe>
<script>
console.log(document.querySelector("#buggy").contentWindow.document.readyState);
</script>

(the exact html i used when i noticed the bug is available here: https://pastebin.com/LHffBgBv )

Actual results:

i got this in my console log:

uninitialized

Expected results:

one of the documented possible values for readyState should have been logged ("loading" or "interactive" or "complete") - for comparison Chromium logged "complete".

Comment 1

[divinity76]

.. sorry, i meant <iframe id="buggy" src="page_that_loads_content_type_text_plain_charset_utf8"></iframe>

• the iframe window loaded content with the HTTP header "Content-Type: text/plain; charset=UTF-8"

idk if that is related, but i thought it might be.

Comment 2

[divinity76]

.. and the documentation i'm referring to is https://developer.mozilla.org/en-US/docs/Web/API/Document/readyState

the value "uninitialized" is not documented there.

Comment 3

[divinity76]

can also reproduce on (the fully up-to-date) 68.6.1esr (64-bit)

Comment 4

[divinity76]

Ok, can also reproduce it on the current stable release: 74.0.1 (64-bit)

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 6

[Firefox Bug Husbandry Bot]

Because this bug's Severity has not been changed from the default since it was filed, and it's Priority is P3 (Backlog,) indicating it has been triaged, the bug's Severity is being updated to S3 (normal.)

Comment 7

[Kagami Rosylight [:saschanaz] (they/them)]

Attachment: bug1627844.html

The iframe is somehow indeed "uninitialized" initially and any modification there immediately disappears when it becomes "complete".