Closed Bug 1474137 Opened 6 years ago Closed 2 years ago

Dynamic datalist doesn't fully update unless backspace pressed


(Toolkit :: Form Manager, defect, P2)




102 Branch
Tracking Status
firefox61 --- wontfix
firefox62 --- wontfix
firefox63 --- wontfix
firefox100 --- wontfix
firefox101 --- wontfix
firefox102 --- fixed


(Reporter: u587052, Assigned: m_kato)


(Blocks 1 open bug)



(1 file)

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:61.0) Gecko/20100101 Firefox/61.0
Build ID: 20180626184830
Firefox for Android

Steps to reproduce:

I've created a reproduce repository here:

1. Open `index.html` directly in a browser
2. Type in the beginning part of "summer" (e.g.: just type "sum")
3. Note that there's no results
4. Hit "backspace" once (input should contain the string "su")
5. There's results again

Actual results:

Firefox didn't show the actual matching datalist - it seems to be showing a subset of results

Expected results:

As I type in "summer", it should show "Summer [Noun]" in the results
Summary: dynamic datalist doesn't update unless backspace pressed → dynamic datalist doesn't fully update unless backspace pressed
I've uploaded the reproduce demo to
I managed to reproduce this issue both by the uploaded link and by dragging the downloaded HTML in the browser on Firefox 61.0.1, 62.0b7 and Nightly 63.0a1 (2018-07-11), Ubuntu 16.04.
Component: Untriaged → DOM: Core & HTML
Ever confirmed: true
Product: Firefox → Core
See Also: → 1340459
Version: 61 Branch → Trunk
Priority: -- → P3
This isn't related to the @autocomplete attribute so removing the See Also.
See Also: 1340459
My previous messages were based on commit "1c64e6f686e3d489dac0228c48c05d0e7f9520c8" for the reproduce demo.

To make locating the bug easier, I've simplified the demo in commit "eb3e0d6bbd44664bccbf1dd4110bd77e501b5f0b" to reproduce the issue without involving any network requests.

The reproduce conditions for the demo are now a little bit different and more intuitive:

1. Open directly in a browser
2. Type the letter `s` and wait for the datalist to update (should show five items)
3. Append the letter `u` (search should be `su` now). Note that only `su1` and `su2` appear in the dropdown, even though (by inspecting the DOM) it's clear that there should be five options
4. Complete the input character-by-character until it contains the word `summer`. Note that the autocomplete dropdown isn't shown at all.
5. Hit backspace once (input should contain `summe`). Note that there's now three results in the dropdown, even though there wasn't any before (even when you had the exact same text in the input).
Workaround: on the <input>, set autocomplete="off"
See Also: → 1351483

This is because we use the cached result for filtering if the results for what the user typed is now a subset of what the user had previously typed. We could disable this caching for datalist searches I guess.

setting the autocomplete attribute to off does not reliably fix the behavior in my case.

Looks like is a duplicate of this bug

For people who do use the autocomplete=off workaround, note that it (currently) breaks the datalist on Firefox for Android. I ended up using JS to set autocomplete=off only if navigator.userAgent indicates that the browser is desktop Firefox.

This workaround works for me: after change datalist dynamically with JavaScript, set input autocomplete to "off" and immediately change it back to "on".

I have this issue, too.

  1. Go to
  2. Type "foobar@" in the email box.

It show dropdown in Chrome but not in Firefox until you press backspace.

Correct previous message:

  1. Go to
  2. Type "foobar@" in the email box.
Component: DOM: Core & HTML → Form Manager
Priority: P3 → P2
Product: Core → Toolkit
Summary: dynamic datalist doesn't fully update unless backspace pressed → Dynamic datalist doesn't fully update unless backspace pressed

Running into the same problem as this bug - it's P2; any chance someone will be looking at this soon? Disabling caching should not be too hard, right?

Blocks: input-list

Even if <datalist> is dynamically changed, autocomplete controller still uses
previous search result. If changed, we have to ignore previous result that may
be invalid.

Also, even if <datalist> is changed, we have to keep selected index (Bug
595069), so we cannot use ResetInternalState at this situation. It resets
selected index.

Assignee: nobody → m_kato

Makoto, I see you have a patch here and we have duplicates? Any news on this bug?

Flags: needinfo?(m_kato)

(In reply to Pascal Chevrel:pascalc (pto until November 2) from comment #19)

Makoto, I see you have a patch here and we have duplicates? Any news on this bug?

Actually, I am busy for other bugs. No update for this. I need a lot of changes to review this again according to review comment.

Flags: needinfo?(m_kato)
Pushed by
Invalidate previous result when datalist is changed. r=mak
Closed: 2 years ago
Resolution: --- → FIXED
Target Milestone: --- → 102 Branch

This is a longstanding bug. No need to uplift the fix to Beta 101.

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