[JENKINS-21613] f:combobox may break form.onsubmit

[ikedam]

f:combobox prevents form submission when the dropdown is open.
This is done by interrupting form.onsubmit.
It handles form.onsubmit in the following way:

1. ComboBox saves the original onsubmit handler in its initialization.
2. When the combobox is selected, it shows the dropdown and overwrites the onsubmit handler. The ovirridden onsubmit prevents form submission of the dropdown is open.
3. When the dropdown is closed, recovers the saved form.onsubmit.

If the form.onsubmit was overridden between step 1 and 2, it would be overridden in step 3 and lost.

This change saves the original onsubmit handler just before overriding it.

[cloudbees-pull-request-builder]

core » jenkins-core #116 SUCCESS
This pull request looks good

[oleg-nenashev]

This JENKINS-21613 becomes annoying in the case of using "Apply" hotkey.
Any "autosave" plugin (if such feature exist somewhere) may suffer from the issue.

+1

[oleg-nenashev]

retriggering the PR.
BTW I feel my comments have not been addressed

[ikedam]

BTW I feel my comments have not been addressed

I might misunderstood your comment.
Do you mean this request cause a problem for the case of using "Apply" hotkey ?
I don't get how the problem occurs.

Anyway, new plugins should use Behavior mechanisms for onsubmit events and they shouldn't be affected by JENKINS-21613, and this request is completely deprecated.
I'm thinking of closing this request and JENKINS-21613 with "Won't fix".

[daniel-beck]

@oleg-nenashev Ping

Also, @jenkinsci/code-reviewers

[oleg-nenashev]

@ikedam @daniel-beck
Went through the code again. I'm actually fine with the approach. I'm not sure what my comment from Jun 11 meant

[oleg-nenashev]

I see no reason why we keep it unmerged.

[oleg-nenashev]

Retriggering CI

[oleg-nenashev]

@ikedam Could you please re-merge with the master to retrigger CI? https://ci.jenkins.io/job/Core/job/jenkins/job/PR-1111/9/console

IIUC one cannot just retrigger it after the recent changes in PR handling by @rtyler and @daniel-beck

[daniel-beck]

I don't understand the problem well enough to have an opinion on this.

[oleg-nenashev]

On hold till it's remerged with master

[ikedam]

Rebased to master (no conflicts) to re-trigger the CI.

combobox.js is really old-fashioned, and it might be better to reform it in the modern way (e.g. using event listeners).
Anyway, I believe this change makes combobox.js a little safer and is good to merge.

[daniel-beck]

@ikedam Could you provide an example how the previous implementation could lead to problems? It's unclear to me how this works.

[ikedam]

@daniel-beck This issue can cause a problem when a component (component X) tries to hook onsubmit event by decorating form.onsubmit in this way:

1. Initialization of combobox.js. It saves form.onsubmit.
2. Initialization of the component X. It decorates form.onsubmit to hook onsubmit event.
3. Onfocus of combobox.js fires. It decorates form.onsubmit to hook onsubmit event.
4. Onblur of combobox.js fires. It restores form.onsubmit to the state of 1. This results the decoration of 2 loses.

This can be fixed in any of following ways:

A. Uses addEventListener to hook events. (This wasn’t an option when I created this request as IE8- had problems in event handlings)
B. Initialize the component X before combobox.js. This can be done by specifying the priority order in Behavior.register.
C. (This request) Save form.onsubmit not when component initialization but when just before decorating it.

I found this issue when I developed the first version of extensible-choice-parameter-plugin.
It developed targetting Jenkins 1.466, and found it get broken with Jenkins1.480+.
That plugin uses a customized combobox and hit this issue.
ikedam/extensible-choice-parameter#3
jenkinsci/extensible-choice-parameter-plugin@66a0103#diff-3f9234fad1a0c518288418c0f36e1ba6

I fixed that problem in the way same to this request and wanted to apply the same change to core as it seemed a fundamentally unsafe behavior even though there’re workarounds as described above.

[daniel-beck]

@ikedam Thanks for the explanation.

[oleg-nenashev]

Fine with me, reconfirm my feedback