[JENKINS-58240] - Plugins should be able to provide onBlur for codemirror textarea.

[rudolfwalter]

Currently, plugins cannot cleanly provide a custom onBlur handler for their codemirror textareas, because it is being overridden in core. This has been the case since 4e48eaa, but it does not look like that side-effect has been intentional.

(Plugins could work around this in a hackish way, by adding })// at the end of their codemirror-config.)

Proposed changelog entries

• RFE, internal: Allow plugins to provide onBlur() handlers for codemirror textarea controls

[daniel-beck]

@rudolfwalter Could you point to a bug in a plugin as the result of this, or a plugin needing to implement this, to illustrate the benefits of this change?

[rudolfwalter]

Sure. I came across this while making jenkinsci/script-security-plugin#255. I added the workaround hack there, and could have left it at that, but thought it would be nicer to actually get it fixed in core so that the hack can be cleaned up later.
Also, I tried to be as backwards and forwards compatible with both changes as possible.

[varyvol]

@rudolfwalter my only concern: if a plugin has already implemented the workaround, would it still work properly if this is included?

[rudolfwalter]

@varyvol It should, yes:

• the plugin-provided part continues to be surrounded with ({ ... }) and processed with eval
• after the eval we check if an onBlur has been provided, and only set it if it wasn't.

[rudolfwalter]

I can only think of one regression that this could cause: in the case when a plugin provided a wrong onBlur, never noticing its error because its onBlur was being ignored; that error would surface after this change.

[varyvol]

@rudolfwalter I don't see that as a regression but as an error in the plugin, so it could even be positive. Thanks for the explanations!

[oleg-nenashev]

AFAICT, it will address the described issue. It would be great to have a JIRA ticket so that we can consider it for backporting

[oleg-nenashev]

Created https://issues.jenkins-ci.org/browse/JENKINS-58240

[oleg-nenashev]

@rudolfwalter Thanks for the patch! I will get it merged once the CI rerun completes. If you want it to be backported to LTS, please comment in the JIRA ticket