1570703 - Watch Expressions should always show up-to-date values.

Status: NEW

(DevTools :: Debugger, enhancement, P3)

Description

[Jason Laster [:jlast]]

It would be great if watch expressions always showed the up-to-date value.

We can implement this by registering watch expressions with the server and having the server periodically (100ms) re-evaluate the expressions and send the client updates if the values have changed.

DETAILS:

1. the server should send one message with the results for all of the expressions
2. the server should evaluate expressions when pausing and include the results in the pause packet

FOLLOW UPS:

1. it would be nice to re-evaluate expressions after console evaluations
2. it would be nice to re-fetch scopes after console evaluations and perhaps highlight changes.
3. it should be possible for the console to register expressions as well. See live expressions

Comment 1

[:Harald Kirschner :digitarald]

The UI could either have a flip to make expressions live, or even better be automatic – making expressions live when the Debugger is not paused. Only risk is that watch expressions execute in the paused scope, so their live value would not necessarily be useful.

Having a holistic integration that mirror live watch expressions in the Console for tracking, similar to Chrome's Live Expressions makes this feature discoverable for more users.

Comment 2

[David Walsh :davidwalsh]

This would be a really cool feature. My only concern with polling for value is that we aren't presently tying the expression to a URL or domain, so polling could be expensive. For example, I will occasionally add watch expressions and, not paying attention to them later, will notice I still have the same watch expressions. I guess any hesitance I have would be over how we persist them.

Comment 3

[Jason Laster [:jlast]]

:plus1: harald

that's a good point david. We'd hate for the common case to basically DDOS your tab :)

One aspect that is nice with this design is that the evaluation is done in the server, so if the value is always undefined the client never heres about it.

Comment 4

[Jason Laster [:jlast]]

Attachment: Bug 1570703 - Watch Expressions should always show up-to-date values. r=davidwalsh

Comment 5

[Jason Laster [:jlast]]

this is just a prototype

Comment 6

[Jason Laster [:jlast]]

Next Steps:

1. add a feature flag defaulted to on
2. add onboarding UI
   3 add dynamic interval based on expression evaluation times
3. update PRD w/ proper milestones
4. should we rename the panel

Comment 7

[Hubert B Manilla]

Attachment: Bug 1570703 - Watch Expressions should always show up-to-date values. r=jlast

wip live expressions

Comment 8

[Jan Honza Odvarko [:Honza] (always need-info? me)]

Hubert, are you still planning to work on this bug?

Honza

Comment 9

[Hubert Boma Manilla (:bomsy)]

No , i'm not sure i'll have time to get back to it soon.

Comment 10

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

The bug assignee didn't login in Bugzilla in the last 7 months.
:bomsy, could you have a look please?
For more information, please visit auto_nag documentation.

Comment 11

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

The following patch is waiting for review from an inactive reviewer:

ID	Title	Author	Reviewer Status
D43826	Bug 1570703 - Watch Expressions should always show up-to-date values. r=jlast	bomsy	nchevobbe: Resigned from review

:bomsy, could you please find another reviewer or abandon the patch if it is no longer relevant?

For more information, please visit auto_nag documentation.

Comment 12

[Hubert Boma Manilla (:bomsy)]

Abandoned the revision. Not in focus atm.